Defibrillator

ABSTRACT

Several defibrillators, defibrillator architectures, defibrillator components and methods of operating defibrillators are described. In one aspect, a defibrillator (as for example an automated external defibrillator) that can be powered by a mobile communication device such as a smart cellular phone or a tablet computer is described. Utilizing a phone (or other mobile communication device) as the power supply for an external defibrillator allows the external defibrillator to be smaller and, in some circumstance, removes the need for a battery that stores sufficient energy for shock delivery—which would need to be checked and/or replaced on a regular basis. Additionally, when desired, certain control functionality, computation, data processing, and user instructions can be handled/presented by the mobile communications device thereby further simplifying the defibrillator design and improving the user experience. This architecture takes advantage of the nearly ubiquitous availability of smart phones, tablet computers and other mobile communication devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.15/835,152, filed on Dec. 7, 2017, which claims the priority of U.S.Provisional Patent Application No. 62/433,067, filed Dec. 12, 2016,62/566,896 filed Oct. 2, 2017 and 62/576,228 filed Oct. 24, 2017, all ofwhich are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present disclosure relates generally to defibrillators and many ofthe inventions described herein are particularly applicable to automatedexternal defibrillators designed to be charged by and used inconjunction with a mobile communication device.

BACKGROUND

Sudden cardiac arrest is one of the leading causes of death. In theUnited States alone, roughly 300,000 people die each year from suddencardiac arrest. It is the leading cause of death for individuals over 40and the #1 killer of student athletes. The most effective treatment forsudden cardiac arrest is the use of CPR coupled with defibrillation.Automated external defibrillators (AEDs) are portable devices designedto automatically check for life-threatening heart rhythms associatedwith sudden cardiac arrest and to send an electrical shock to the heartto try to restore a normal rhythm when shockable heart rhythms aredetected. The two most common conditions treated by AEDs are PulselessVentricular tachycardia (aka VT or V-Tach) and Ventricular fibrillation(VF or V-Fib). AEDs are typically designed such that they can be used bya lay person in situations where professional medical personnel are notavailable.

Given their potential to save lives, automated external defibrillatorshave been deployed in a relatively wide variety of public and privatelocations so that they are available in the event that a person in thevicinity goes in to cardiac arrest. By way of example, AEDs may be foundin corporate and government offices, shopping centers, airports,airplanes, restaurants, casinos, hotels, sports stadiums, schools,fitness centers and a variety of other locations where people maycongregate. Although the availability of AEDs has increased over theyears, their relatively high cost tends to limit their placement andmany locations including schools, sports fields, and a plethora of otherplaces where people congregate don't have an on-site AED available.Furthermore, although many AEDs are considered “portable”, mostcommercially available portable automated external defibrillators arebulky and heavy enough that they are rarely carried by people other thantrained medical personnel. Thus there are many times, locations andevents where no AED is available when a cardiac arrest incident occurs.Even when an AED is nearby when a sudden cardiac arrest incident occurs,the AED is often not used because either its presence is unknown or thedevice seems intimidating to bystanders who are reluctant to try to usea device that they are unfamiliar with.

Although existing AEDs work well, there are continuing efforts todevelop AEDs that have characteristics likely to broaden the deploymentand availability of automated external defibrillators.

SUMMARY

Several defibrillators, defibrillator architectures, defibrillatorcomponents and methods of operating defibrillators are described. In oneaspect, a defibrillator (as for example an automated externaldefibrillator) that can be powered by a mobile communication device suchas a smart cellular phone or a tablet computer is described. Utilizing aphone (or other mobile communication device) as the power supply for anexternal defibrillator allows the external defibrillator to be smallerand, in some circumstance, removes the need for a battery that storessufficient energy for shock delivery—which would need to be checkedand/or replaced on a regular basis. Additionally, when desired, certaincontrol functionality, computation, data processing, and userinstructions can be handled/presented by the mobile communicationsdevice thereby further simplifying the defibrillator design andimproving the user experience. This architecture takes advantage of thenearly ubiquitous availability of smart phones, tablet computers andother mobile communication devices.

In some embodiments, the defibrillator is an AED suitable for use withan operator's personal smart phone and/or other types of personalcommunication or computing devices. In other embodiments, a dedicatedsmart phone is packaged together with the defibrillator. In still otherembodiments, many of the features described herein are well suited foruse in more conventional defibrillator architectures that are notnecessarily intended for use in conjunction with a mobile communicationdevice.

In various embodiments, the defibrillator includes a shock deliverycapacitor and charging circuitry that includes voltage boostingcircuitry that boosts the voltage of received current to charge theshock delivery capacitor.

In another aspect, various defibrillator charging circuitry isdescribed. In some embodiments, the charging circuitry includes currentregulating circuitry configured to maintain a current draw from a powersource for the voltage boosting circuitry throughout the charging of thecapacitor. In some embodiments, the current regulating circuitryincludes a transitory electrical energy store that serves as a temporarystore for electrical energy drawn for a power source during the voltageboosting circuitry's current shut-off intervals and as a supply ofsupplemental current to the voltage boosting circuitry during at leastportions of the periodic current draw intervals. In some embodiments,the current regulating circuitry may include a digitally controlledcurrent limiting Buck converter.

In another aspect, various flyback converter designs are described. Insome embodiments, the voltage is boosted by a flyback converter—which insome specific embodiments takes the form of a valley switching flybackconverter or more generally, a variable frequency flyback converter. Inother embodiments, a maximum current through the primary coil of theflyback converter may be set programmably at the time of charging of thecapacitor unit to help regulate the charging circuit's current draw. Insome embodiments, the maximum primary coil current level is periodicallyadjusted during charging of the capacitor based at least in part on athen present measured voltage of the capacitor unit.

In another aspect defibrillators having various current regulatingcircuitry are described. In some embodiments, a defibrillator controlleris arranged to set selected parameters of the current regulatingcircuitry in order to maintain a draw current from a mobilecommunication device (or other available power supply) at a level thatis near, but does not exceed a maximum draw current associated with themobile communication device. In some embodiments, such parameters may beset and reset by the defibrillator controller during charging of thecapacitor unit to help maintain a desired current draw. Any of a numberof different charging circuit parameters can be set by the defibrillatorcontroller, as for example, the capacitance or inductance of thetransitory electrical energy store, a maximum current level for thecurrent draw from the power source (e.g., the mobile communicationdevice) or for a particular component such as the primary coil of atransformer, a minimum current level for the current draw from the powersource, etc.

In some embodiments, the current regulating circuitry includes a currentsensor for sensing the current drawn from the power source and acontroller (which may optionally be the defibrillation controller) thatreceives a sensed input current from the current sensor and turns aninput switch of the voltage boosting circuitry on and off to maintainthe current drawn from the power source within a designated rangethroughout the charging of the capacitor.

In a separate, more general aspect, some of the described circuitregulating circuits may be used to continuously draw current for voltageboosters used in devices other than defibrillators that are powered by amobile communication device.

In another aspect a defibrillator may be arranged to automatically begincharging the capacitor when the defibrillator is initially activated. Insome embodiments, the charging automatically begins when thedefibrillator is initially connected to a mobile communication device.In other embodiments, the charging automatically begins when thedefibrillator is manually activated by a user or in response to otherspecific triggers.

In various embodiments, the defibrillator may be connected to a mobilecommunication device through a connector cable that may be plugged intothe mobile communication device. In other embodiments, the defibrillatorand the mobile communication device are connected wirelessly—as forexample through the use of inductive charging and the use of a shortrange wireless communication protocol.

In some embodiments the defibrillator does not include an energy storagedevice (such as a battery) that can be used to charge the dischargecapacitor and is capable of holding sufficient energy to facilitatecharging the capacitor to deliver a defibrillation shock to a patient.In other embodiments, the defibrillator includes an internal powersupply arranged to provide power or additional power for charging thecapacitor unit.

In some embodiments, an app is installed on the mobile communicationdevice and may be used to at least partially control the defibrillatorduring its use.

In some embodiments the defibrillator includes a bleed circuit thatslowly drains the capacitor such that the capacitor will not retain acharge for a prolonged period of time. In some embodiments, the bleedcircuit is a voltage sensing circuit arranged to measure a voltage ofthe capacitor.

In yet another aspect, housings for defibrillators are described. Insome embodiments, the defibrillator may include an elongated tubularhousing having an external opening at a first end of the elongatedtubular housing. Defibrillator electronics are positioned within theelongated tubular housing and a removable end cap may be provided tocover the external opening. In some embodiments, a pair of defibrillatorpads and/or an electrical connector cable may be stored within thehousing and be made accessible when the end cap is removed. In someembodiments, end caps are provided on both ends of the tubular housing.

In another aspect, in some embodiments, the elongated tubular housinghas a substantially oval or stadium shaped cross section and/or has atleast one flat edge.

In some embodiments, the end cap forms a watertight seal with the firstend of the tubular housing. In some embodiments the end cap has a pullfeature configured to be pulled to remove the end cap from the first endof the housing.

In some embodiments, the defibrillator electronics includes a firstcircuit board that carries low voltage components and a second circuitboard that carries high voltage electrical components.

In some embodiments, the defibrillator further includes a battery packthat couples to the housing.

In yet another aspect, housings for defibrillators having integratedmobile devices are described. In one such embodiment, the housing hasfirst second and third compartments. The first compartment holds amobile communication device having a display screen that is exposedthrough a first external housing opening. The second compartment holds apair of defibrillator pads which are accessible through a secondexternal housing opening. The third compartment holds the defibrillatorelectronics. In some embodiments the housing has a gem shaped crosssectional area.

In another aspect, various methods of charging a defibrillator dischargecapacitor are also described. In some embodiments, a maximum drawcurrent for a discharge capacitor charging circuit is set based at leastin part on a current delivery capability of a connected power supply,such as a connected mobile communication device. In some embodiments,the defibrillator is suitable for connection to multiple different typesof devices having different current delivery capabilities. In suchembodiments, different maximum draw currents can be specified forcharging the capacitor unit to facilitate efficient use of such devices.

In some embodiments, a maximum current through a primary coil of atransformer is set at the time of charging based at least in part on acurrent delivery capability of the power supply. In some embodiments,the maximum current through the primary coil is changed during thecharging of the defibrillator discharge capacitor based at least in parton a then present voltage or charge level of the defibrillator dischargecapacitor.

In some embodiments, a variable electrical characteristic of atransitory electrical energy store is changed during charging of thecapacitor unit based on the discharge capacitor charge level. In someembodiments, an input switch of the voltage boosting circuit is turnedon and off to maintain the current drawn from the power source within adesignated range.

In some embodiments, a continuous current draw from a power source ismaintained for a voltage boosting circuit using a transitory electricalenergy store. The transitory energy store serves has a temporary storefor electrical energy drawn from the power source during the voltageboosting circuitry's periodic current shut-off intervals and as a supplyof supplemental current to the voltage boosting circuitry during atleast portions of the periodic current draw intervals.

In some embodiments, charging of a shock delivery capacitor isautomatically initiated when the defibrillator unit is initiallyconnected to the mobile communication device.

In yet another aspect, various approaches to controlling the delivery ofa defibrillation shock are described. In some embodiment, adefibrillator controller determines the desired duration of a shockpulse based at least in part of a discharge capacitor voltagemeasurement taken during the delivery of the defibrillation shock pulse.In this approach, the impedance of the patient is effectively determinedon the fly during shock delivery using the voltage measurements andknown characteristics of the discharge capacitor.

In yet other aspects, various apps and/or other software or firmwarebased control routines are described that are well suited forcontrolling various aspects of the use and/or operation of adefibrillator. An app or other suitable software construct can haveprogrammed instructions stored in the memory of a computing device suchas a mobile communication device.

In some embodiments, an app on a mobile communication device isconfigured to transmit an indication of a parameter to the defibrillatorthat is indicative of, or can be used by the defibrillator to determine,the mobile communication device's current delivery capabilities. In someembodiments, the app includes programmed instructions for analyzingheart rhythms received from the defibrillator unit to determine whethera patient has a shockable heart rhythm.

In some embodiments, the app is configured to automatically authorizedelivery of current from the computing device to the defibrillator unitin response to the connection of a defibrillator unit to the computingdevice.

In some embodiments, a defibrillator control app is configured togenerate an event history log that records a history associated with theuse of an associated defibrillator for a particular event. The eventhistory log may include a shock history that includes an indication ofthe number of shocks delivered, an indication of the energy chargeutilized in each applied shock associated with the event and the timethat each applied shock associated with the event was administered. Theapp can also be configured to display an event history GUI element on adisplay screen of the mobile communication device. Selection of theevent history GUI element causes an event history frame to be displayedon the display screen. The event history frame shows the number ofshocks delivered, the energy charge utilized in each applied shockassociated with the event and the time that each applied shockassociated with the event was administered.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and the advantages thereof, may best be understood byreference to the following description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a diagrammatic illustration of an automated externaldefibrillator ready for deployment in accordance with one embodiment ofthe invention.

FIG. 2 is a circuit block diagram illustrating an electronicsarchitecture suitable for use in a defibrillator such as the AED of FIG.1.

FIG. 3 is a schematic circuit diagram of a digitally controlled currentlimiting Buck Converter.

FIG. 4 is a schematic circuit diagram of a parallel boost convertersuitable for use in the described defibrillators.

FIG. 5A is a schematic circuit diagram of a valley switching flybackconverter based discharge capacitor charging system in accordance withanother embodiment.

FIG. 5B is a schematic circuit diagram of an alternative defibrillatorelectronics architecture that utilizes the valley switching flybackconverter of FIG. 5A.

FIG. 6 is a circuit diagram illustrating a representative flybackconverter.

FIGS. 7A-7C are graphs respectively illustrating the primarily coilcurrent, the secondary coil current and the switch drain voltageassociated with a charging cycle of the representative flyback converterillustrated in FIG. 6.

FIG. 8 is a graph illustrating the switch drain voltage associated witha charging cycle of a valley switching flyback converter.

FIG. 9 is a flow chart illustrating a discharge capacitor chargingscheme.

FIG. 10 is a schematic circuit diagram of a discharge circuit suitablefor use in some of the described defibrillators.

FIG. 11A is a graph illustrating a representative shock waveformgenerated by a pair of equally sized, oppositely polarized dischargecapacitors in accordance with another embodiment.

FIG. 11B is a graph illustrating potential target waveforms fordelivering a 150 Joule biphasic shock in patients having 50, 75 and 100ohm resistances respectively between the pads.

FIG. 12 illustrates a discharge circuit suitable for use with oppositelypolarity capacitors.

FIG. 13 is a flow diagram illustrating a process flow suitable forcontrolling the described defibrillators.

FIG. 14 is an exploded view of the defibrillator illustrated in FIG. 1.

FIG. 15A is a perspective view of an alternative tubular defibrillatorhousing embodiment that has a single end cap.

FIG. 15B is an end view of the tubular defibrillator housing illustratedin FIG. 15A.

FIG. 16 is perspective view of another alternative defibrillatorembodiment that includes an embedded smart phone.

FIG. 17 is a perspective view of the housing of FIG. 16 alone with itsend cap removed.

FIG. 18 is a perspective view of another alternative defibrillatorembodiment that also includes an embedded smart phone.

FIG. 19 is a flow chart illustrating a shock discharge control approachthat utilizes dynamic shock pulse timing determination.

FIG. 20 is a perspective view of a defibrillator that utilizes inductivecharging to delivery electrical energy to the charging circuit.

In the drawings, like reference numerals are sometimes used to designatelike structural elements. It should also be appreciated that thedepictions in the figures are diagrammatic and not to scale.

DETAILED DESCRIPTION

Referring initially to FIG. 1, a portable defibrillator architecture inaccordance with one embodiment of the invention will be described. Theillustrated architecture is well suited for use in automated externaldefibrillators (including both semi-automatic and fully automaticdefibrillators) although it may also be used in manual defibrillatorsand hybrid defibrillators that may be used in either automated or manualmodes. The core of the portable defibrillator system 100 is adefibrillation unit 110 which is preferably used in conjunction with amobile communication device 105 such as a cell phone, a tablet computer,a personal digital assistant (PDA) or other portable computing device.The system 100 also includes a connector cable 113 and pair ofdefibrillator pads 116. In the illustrated embodiment, the mobilecommunication device takes the form of a smart phone such as a SamsungGalaxy or an Apple iPhone. However, in other embodiments, a wide varietyof other mobile communication devices may be used in place of the smartphone. Power for the defibrillation unit 110 is obtained from the phone105, which eliminates the need to provide batteries or other long termenergy storage devices that store sufficient energy for shock deliveryas part of the defibrillation unit.

In some preferred embodiments, the defibrillation unit 110 is designedto be used in conjunction with an app 108 that is installed, orinstallable on the mobile communication device. This permits use of theprocessing power of the phone to handle some of the signal processing,control and user interface functions required of the defibrillatorsystem.

The defibrillator unit 110 houses electrocardiography circuitry fordetecting electrical activity of a heart of a patient and shock deliverycircuitry for delivering a defibrillation shock to the patient whenappropriate. The defibrillation unit 110 preferably also houses theconnector cable 113 and the defibrillator pads 116 when the unit isstored. To use the defibrillator, the connector cable 113 is plugged into the I/O connector on the phone 105. The defibrillation unit 110 ispreferably configured to begin charging the shock delivery circuitry assoon as it is plugged into the phone. In the illustrated embodiment,connector cable 113 takes the form of a micro USB cable because theillustrated phone 105 has a micro USB connector. However in otherembodiments, the cable can include any form that is appropriate forconnection to the phone's I/O connector—as for an example, a lighteningcable/connector, any other type of USB connector, including a USB-Ccable/connector, a 30 pin dock cable/connector, etc.

Any of a variety of commercially available defibrillator pads may beused as defibrillator pads 116. Typically the defibrillator pads areadhesive so that they can be securely attached to a patient at the timeof a sudden cardiac event. If desired separate pads can be provided foradult and pediatric applications.

The medical community has established a variety of recommended externaldefibrillation shock protocols. These protocols typically call for thedelivery of an electrical shock on the order of 120-200 joules at avoltage on the order of 1400-2000V for an adult when a biphasicdefibrillator is used. More energy, as for example 200-360 joules istypically required if a monophasic defibrillator is used. Considerablylower shock intensities are recommended for pediatrics applications. Therecommended shock guidelines can vary with the age/size of the patientand the nature of the heart rhythms that are detected. The defibrillatorelectronics can be configured to deliver any shock protocol deemedappropriate for the specific event.

Electronics

FIG. 2 is a block diagram illustrating a first electronics architectureand associated components suitable for use in a defibrillator. In theillustrated embodiment, the electronic components include a controller202, a current regulator circuit 205, a voltage booster 207 (which mayhave multiple stages), a high voltage capacitor 209 for temporarilystoring sufficient electrical energy suitable to provide adefibrillation shock, discharge control circuitry 220, ECGsensing/filtering circuitry 225 and relays 229. The current regulator205 and voltage booster 207 which cooperate to control the charging ofthe capacitor 209 are sometimes referred to herein as a charging circuit208.

When the defibrillator unit 110 is connected to the phone via connectorcable 113 there are at least three lines over which connections aremade. They include a power supply (typically, 5V), a ground (GND) andone or more serial communication lines between the defibrillatorcontroller 202 and a processor on the phone. The controller 202 (whichmay take the form of a microprocessor) communicates with the processoron the phone via the serial line(s) on the connector cable.

In one particular implementation, a USB OTG (on the go) connection ismade, which allows the phone to essentially become the “host” that isable to control the processor on the defibrillator. The internal wiringof various USB OTG cables may vary. For example, a type B micro-USB OTGcable is a five pin USB plug. It has +5V, GND, two lines for Data+ andData− that work together to become the serial communication. The fifthline is the “sense” line that indicates that the device is in host mode.In another example, a type C USB OTG cable has 12 pins, again with pinsfor GND, power and serial communication.

The controller 202 is configured to control the state of relay 229 andto switch the various components of the defibrillator between the ECGreading and discharge states. The controller 202 also cooperates withthe app 108 to manage and control the AED during use. In applicationswhere the app 108 provides primary control over the process flow, themicroprocessor acts as the “middle man” that orchestrates the electroniccomponents in accordance with the app's instructions. In such anembodiment, the microprocessor 202 receives commands from the phone, andreturns to the phone whatever has been asked of it. For instance, if thephone asks for the capacitor charge, the processor 202 will return anindication of the scaled voltage. If the phone asks for confirmationthat the electrode pads are connected, the microprocessor will return anindication verifying their connection. If the phone asks for the ECGreading, the microprocessor will send the ECG signal being taken fromthe pads attached to the body back over the serial line. If the phoneinstructs a shock to be delivered, the microprocessor will set theappropriate pins in order to drive the HV system to deliver the shock.In other embodiments, the controller 202 may orchestrate more of theoverall process flow.

The power supply (typically, but not necessarily 5V) is used both topower the electronics carried on the defibrillator unit 110 and tocharge the high voltage capacitor 209. Thus, voltage booster 207 isarranged to boost the voltage from 5V to the desired operational voltageof the discharge capacitor 209, which in the described embodiment may beon the order of approximately 1400V-2000V (although the defibrillatormay be designed to attain any desired voltage). In a particularembodiment a multi stage boost converter is used with a first stagebeing used during lower voltage periods of the charging and the secondstage being used during higher voltage periods of the charging. By wayof example, in one implementation each stage is a proportional boostconverter circuit and the stages are arranged in parallel. The firststage is used to charge capacitor 209 to an intermediate thresholdvoltage such as 800 volts, and the second stage is used to charge thecapacitor at voltages above the threshold. An advantage of usingmultiple stages is that each stage can boost more efficiently in itsoperational range. Of course, the specific threshold(s) used and thenumber of stages employed may vary widely.

By way of example, FIG. 4 is a schematic circuit diagram of a suitabletwo stage parallel boost converter. In the illustrated embodiment,parallel boost converters 207(a) and 207(b) are each fed 5V power fromcurrent regulator 205. Each boost converter 207(a) 207(b) has acorresponding enable line 241(a), 241(b) coupled to the controller 202.The controller directs when each of the boost converters are turned onusing their respective enable lines 241. When the boost converter isturned on, its voltage boosted output is fed to the capacitor 209 tothereby charge the capacitor. In the illustrated embodiment, diodes 243are provided to prevent current from flowing in the reverse direction,although it should be appreciated that other suitable structures orarrangements may be used to accomplish the same function. The boostconverters 207 may be implemented using discrete circuitry, integratedcircuit boost converter chips or in other suitable manners. By way ofexample, in some implementations a FS20 module available from XP Powermay be used.

In other embodiments the voltage boosting can be accomplished in asingle stage or in multiple stages and the magnitude of the voltageboost provided by each stage may be varied as appropriate. In stillother embodiments, the stages can be operated in parallel. The two stageboosting described has some cost/efficiency advantages based oncommercially available parts.

The current regulator 205 ensures that the charging circuit does notdraw more current than the mobile communication device can provide. Thisis important because many cellular phones and tablet computers havesafety circuits that cut off the delivery of electrical current if toomuch current is drawn at any time. If the defibrillator unit 110 tripsthe safety circuit by drawing more current than permitted by theattached phone, the phone's safety circuit will cut off power from beingdrawn from the I/O port and it may be some time before connector poweris restored—which is undesirable. At the same time, during charging ofthe capacitors, it is desirable to draw very close to as much power asthe phone has the ability to provide because the charge time isinversely proportional to the drawn current. Therefore, restricting thecharging current draw to a level noticeably below the maximum currentthat can be drawn from the phone will cause unnecessarily slow charging.Thus, a goal for the current regulator 205 is to maintain the currentdrawn from the phone at a level that is very close to, but is assurednot to exceed, the maximum current that is known to be obtainable fromthe phone. Preferably, current is drawn substantially continuously fromthe phone, rather than in periodic bursts dictated by the voltageboosting circuitry as is common in most transformers and other voltageboosting circuits.

By way of example, limiting the charging current to just under 500 mAhas been found to work well with most older smart phones includingphones ranging from various older Blackberries to Samsung Galaxy SS/S6.This is because many such phones utilize USB 2.0 or similar connectorsand the USB 2.0 specification calls for the delivery of 500 mA at 5V.Even these current draw rates facilitate charging the capacitor 209sufficiently to deliver a 150 joule defibrillation shock within anappropriate period based on the expected set-up time for defibrillationfor the first shock and the recommended interval between shocks for anysubsequent shocks that may be advised (defibrillation shocks aretypically recommended every two minutes if necessary duringresuscitation). Most newer phones support significantly higher currentdraw rates which facilitate even faster charging. By way of example,phones utilizing USB 3.0 connectors are typically able to continuouslydeliver 900 mA at 5V and many modern phones support significantly highercurrent draws.

In the illustrated embodiment, a digitally controlled current regulator205 is positioned between the controller 202 and the boost converter 207so that it controls the current being delivered to the boost converter,although in other embodiments it may be placed at any other suitablelocation.

The current regulator 205 may take a variety of forms as long as itaccomplishes the intended functions of (1) maintaining the input currentat a generally stable level that is close to, but never exceeds themaximum current that can be delivered by the phone, and (2) keepsparasitic power losses low. A digitally controlled current limiting Buckconverter that is well suited for use as current regulator 205 isillustrated in FIG. 3.

In the embodiment illustrated in FIG. 3, the current regulator 205 is adigitally controlled current limiting Buck converter that includes acurrent sensor 260 (R1, U5) that detects the input current level, an LCcircuit 267 (L1, C1) and a Buck converter 273 (271,D1,L2,C2,C3). In someembodiments, the current sensor 260 may be implemented using a currentsensing chip 262 (U5) that detects the voltage drop across a smallresistor 264 (R1). The resistor 264 is preferably very small—just enoughfor the current sensing chip to be able to detect the voltage dropacross the resistor in order to determine the current flow whileproviding minimal power loss (as for example less than 0.1 Ω). Thesensed current is communicated to a suitable controller, which in thedescribed embodiment is incorporated into defibrillator microcontroller202. With this approach, the controller always knows the instantaneouslevel of current being drawn by the voltage booster 207.

The LC circuit 267 (L1, C1) serves as an input for an input switch 271for Buck converter 273 (O1,D1,L2,C2,C3). Buck converters are generallyknown to be efficient step down voltage converters. The voltage isstepped down while stepping up current with only a small loss of power.In the illustrated embodiment, input switch 271 takes the form of aMOSFET, although other switches may be used in other embodiments. Theon/off state of MOSFET switch 271 is controlled by a current regulatorcontroller—which in this case is incorporated into the functionality ofmicrocontroller 202.

In order to charge the defibrillator capacitor 209, the MOSFET switch271 is turned on and current begins flowing from the source (e.g. theconnected phone) through resistor 264 and inductor L1 into the Buckconverter 273. The presence of inductor L1 causes the current to rise ina generally exponential manner The current sensing chip 262 detects thecurrent being drawn by the voltage boost converter 207 and continuallyreports the value to controller 202. When the current approaches themaximum permissible current threshold, switch 271 is turned off bycontroller 202. At this stage current continues to flow through theinductor L1, passing now into LC circuit capacitor C1 which begins tocharge. As LC circuit capacitor charges, its back voltage increases,thereby causing the current to flow more slowly. When the current dropsto a slightly lower threshold, the switch 271 is turned back on bycontroller 202, at which point current flows into the Buck converter 273from both the inductor L1 and the LC circuit capacitor C1. With the Buckconverter switch 271 open, current through the inductor L1 begins torise again in an exponential manner until it again approaches themaximum permissible current threshold at which point the switch 271 isturned off again. This process is repeated throughout the defibrillatorcharging process.

The switch 271 can be switched very quickly. By way of example, in someimplementations a clock rate on the order of a megahertz is used(although it should be appreciated that the actual clock rate can varywidely). Therefore the upper and lower current thresholds can be quiteclose to each other in magnitude so that the charging current remainsrelatively stable near the maximum permissible draw current for theconnected mobile device 105. For example, if the maximum permissibledraw current is 500 mA, then the upper threshold can be set at on theorder of 495 mA and the lower threshold can be set at on the order of485 mA, which results in a current draw that oscillates between 485 and495 mA. Of course, the specific upper and lower thresholds used may bevaried based on any design criteria considered important to thedesigner.

Several features of this arrangement are particularly noteworthy.Initially, current is continuously drawn from the power supply (e.g. themobile device battery) during the discharge capacitor charging process.This contrasts with traditional defibrillator designs in which the powerto charge a discharge capacitor is drawn from the power supply inperiodic intervals. Additionally, the current is drawn from the powersupply at a relatively constant rate, which again is quite differentthan conventional designs.

Since the controller 202 directs the operation of switch 271, it canreadily adjust the thresholds used without requiring any changes to thecurrent regulating circuitry. Thus, for example, if the connected mobiledevice 105 is capable of delivering 900 mA of current, the thresholdsused by the controller can be set appropriately to maintain a relativelyconstant current draw near 900 mA—as for example, an upper threshold of895 mA and a lower threshold of 885 mA. In practice, any appropriatecurrent limit can be enforced using the described approach. The abilityto programmably set a maximum or desired draw current from the powersupply used to charge the discharge capacitor at the time of use is alsoquite different than conventional designs. It should be apparent that inappropriate circumstances, the maximum or desired draw current can beset to a value that is close to the maximum continuous draw currentauthorized by the device (e.g., the mobile device) powering the chargingof the discharge capacitor.

In the specific example given above, the current regulator 205 isinstructed to maintain a constant current near 500 mA which correspondsto the maximum current draw specified by the USB-2.0 connectorspecification and thus it is believed that most smart phones are capableof supplying at least 500 mA of current at 5 volts. However, otherpopular connector specifications have higher current limits and mostmodern phones/mobile devices permit higher current draws (oftensignificantly higher current draws). For example, USB-3.0, which is usedin many newer phones, supports a current draw of up to 900 mA at 5Vwhich significantly reduces charging time. USB-C connector cablessupport even higher current draws—as for example draw currents of 1.5 or3.0 Amps at 5V.

It should be appreciated that the described current regulator 205 can beused to efficiently control the power draw from a mobile communicationdevice in a variety of other applications as well (e.g.., in devicesother than defibrillators which seek to draw power from a smart phone orother mobile communication device)—and/or in other applications where adevice that needs power may be couple to power supplying devices capableof delivering different current levels.

Some mobile communication device providers such as Apple requirepermission for an external device to draw power from their phones andtablet computers and are understood to have the ability to set highercurrent draws. Therefore, some manufactures may be willing to set highercurrent draws for approved medical applications such as the describeddefibrillators. An advantage of the digitally controlled current limiterdescribed above is that the drawn current can be set to anydesired/appropriate level. Thus, for example, if the defibrillator unit110 is connected to a device capable of delivering 900 mA, then the app108 can instruct defibrillator controller 202 to set the current limiterto a charge current of nearly 900 mA current—which would shorten thecharging time to a designated charge level a corresponding amount. Ingeneral, the current limit can be set to any level that is appropriatefor the connected device. In some embodiments, the app 108 and/or thedefibrillator controller includes a lookup table or other suitableconstruct that can be used to find the appropriate current draw levelfor any particular type of mobile communication device that is connectedto the AED.

A voltage sensor 211 is provided to read the voltage of the capacitor209. The voltage sensor may take the form of a voltage divider or anyother suitable form. This capacitor voltage reading is utilized todetermine when to switch between boost stages and when the AED ischarged suitably for use. The sensed voltage is provided to controller202 which is configured to transmit a ready for discharge message to thephone 105 over cable 113 when the capacitor 209 is charged sufficientlyto deliver a defibrillation shock. In other embodiments, the controller202 can transmit the sensed capacitor voltage to the phone 105 which mayhave logic for determining when the required discharge voltage isattained. It should be appreciated that the capacitor 209 can be chargedto any desired level. This is important because different defibrillationprotocols advise different voltage and/or energy level shocks fordifferent conditions. Furthermore, if the initial shock is notsufficient to restart a normal cardiac rhythm, recommended treatmentprotocols often call for the use of progressively stronger impulses insubsequently administered shocks (up to a point).

Referring next to FIG. 5A, an alternative discharge capacitor chargingcircuit will be described. In this embodiment, a flyback converter isused as the voltage booster circuitry 207 in place of the boostconverters to charge discharge capacitor 209. In some preferredembodiments, a valley switching flyback converter is used.

In the embodiment illustrated in FIG. 5A, capacitor charging circuitry300 includes a transitory electrical energy store 305, a flybackconverter 320, and capacitor voltage sensor 340.

The transitory electrical energy store 305 serves as a temporary storefor electrical energy drawn from the mobile device so that current cancontinue to be drawn from the mobile device even when current to thetransformer is transitorily turned off as part of the flyback convertercontrol. Stored energy is drawn from the transitory electrical energystore to supplement the draw current during periods in which thetransformer is turned on such that the total current fed to thetransformer while the primary transformer coil is on is actually higherthan the current drawn from the mobile device itself. In someembodiments (as for example, the embodiment of FIG. 5A), the transitoryelectrical energy store 305 takes the form of a stacked set ofcapacitors, although it should be appreciated that in other embodiments,different circuitry can be used to accomplish similar functionality. Forexample, in some embodiments, one or more inductors can be arranged inconjunction with one or more capacitors to form the transitoryelectrical energy store—as is illustrated, for example, in thetransitory electrical energy store (the LC circuit 267) utilized in thedigitally controlled current limiting Buck converter of FIG. 3. In stillother embodiments one or more inductors may be used to form thetransitory electrical energy store.

The flyback converter 320 boosts the voltage from the voltage outputfrom the mobile device (typically approximately 5V) to a high voltagesuitable for charging the shock discharge capacitor 209 to itsoperational voltage. As previously discussed, the discharge capacitor209 is typically charged to a voltage on the order of approximately1400V-2000V (although the discharge capacitor may be designed to attainany desired voltage). In some embodiments valley detection flybackconverter control is used.

In a particular embodiment illustrated in FIG. 5A, the flyback converter320 includes a transformer controller 321 and transformer 330, whichincludes primary coil 331 and secondary coil 332. The transformercontroller 321 includes a valley detection switching controller 322, aswitch 324, and a maximum transformer current control circuit 326. Insome embodiments, the valley detection switching controller 322 takesthe form of a dedicated integrated circuit chip such as the LT3750capacitor charging controller available from Linear Technologies (AnalogDevices). The switch 324 is arranged to turn the transformer 330 on andoff. When the switch 324 is turned on, current is drawn into the primarycoil 331 of transformer 330. When the switch is turned off, current nolonger flows into the primary coil. The switch 324 typically takes theform of a FET such as a MOSFET, although other structures can be used asthe switch in other embodiments. Although specific circuitry and chipare illustrated, it should be appreciated that other flyback convertercontrol circuits or control chips, can be used in other embodiments.

In the illustrated embodiment, the flyback converter 320 also includes asnubber circuit 310 that is arranged to smooth voltage transitionsduring switching of the transformer 330, although it should beappreciated that in other embodiments, different circuitry can be usedto accomplish the desired functionality.

Referring next to FIGS. 6-8, the advantages of valley detection controlwill be described. FIG. 6 illustrates a traditional flyback convertercircuit in which a MOSFET switch 424 is used to control the flow ofcurrent through transformer 430. The input side of primary coil 431 isconnected to power (e.g. 5V) and the output side of primary coil 431 isconnected to ground through switch 424. When switch 424 is turned on,current flows through the primary coil 431. When the switch 424 is firstturned on, current I_(pri) begins flowing through the primary coil andincreases until the peak primary coil current I_(pri_peak) is achievedas seen in FIG. 7A. At that stage, the switch 424 is turned off andcurrent I_(sec) begins flowing out the secondary coil 432 and graduallydecays as seen in FIG. 7B. Once the transformer is effectivelydischarged, the secondary coil current I_(sec) stops flowing and voltageon the drain side of MOSFET switch 424 will experience a resonantringdown 451 as illustrated in FIG. 7C. Traditionally, the switch 424 iskept off for a designated waiting (ringdown) period (t_(dead)) that isconsidered long enough to ensure that the MOSFET drain voltage V_(ds)will always have settled to effectively be equal to the input voltage,or at least be below a designated voltage. This is important because ifthe drain voltage V_(ds) is higher than the bus voltage (in the contextof defibrillator unit 110, the input voltage of the phone) when theswitch 424 is turned back on, high switching losses will result, whereasif the drain voltage V_(ds) is lower than the bus voltage, low switchinglosses and high efficiency will result.

After the waiting period is over, the switch 424 may be turned back onand the process is repeated. The period between the time when currentI_(sec) stops flowing through the secondary coil 432 and when the switch424 is turned back on is effectively dead time (t_(dead)) in which thetransformer is not performing useful work. In practice, the dead time(t_(dead)) in many flyback converter designs is often a (tdead)significant percentage (e.g., greater than 40%) of the total flybackconverter cycle period (t_(cycle)) which includes (a) the time (t_(on))in which switch 424 is on with current flowing through the primary coil;(b) The period (t_(demag)) in which current I_(sec) flows (out thesecondary coil 432; and (c) the waiting period (t_(dead)).

Valley detection is used to reduce the waiting period (t_(dead)) beforethe switch 424 is turned back on—which has the effect of improving theoverall charging efficiency. With valley detection, the trough(s) thatoccur in the ringdown 451 are detected. The switch 424 is turned on oncea trough (valley) (preferably one of the first troughs) is detectedthereby beginning the next flyback converter cycle after a much shorterwaiting period (t_(dead)). This can significantly improve the chargingefficiency of the overall capacitor charging circuit, both by limitingt_(dead) as well as facilitating low switching losses when the nextcycle is initiated. Therefore, the charging cycle may look more like thecycle illustrated in FIG. 8. FIG. 8 illustrates an example in which thefirst valley is detected which may occur in some circumstances. In othercircumstances, the valley detector may actually detect and switch on asubsequent valley (e.g., the second or third valley) which stillsignificantly reduces the ringdown waiting period.

As will be appreciated by those familiar with advanced flyback converterdesign, a flyback converter operates in a discontinuous conduction mode(DCM). Valley switching is a specialized form of DCM and is sometimesalso referred to as a variable frequency flyback converter. Aquasi-resonant flyback converter is a specific form of valley switchingoperation, where the switch 424 is always turned on when the firstvalley is detected, thereby achieving the lowest possible switchinglosses. Although only valley detection based discontinuous mode flybackconversion has been described in detail, it should be appreciated thatother types of converters, including other discontinuous mode flybackconverters or continuous conduction mode (CCM) flyback converters may beused in other embodiments.

Returning to FIG. 5A, the illustrated embodiment, the capacitor chargingcontroller 322 is designed so that the maximum primary coil currentI_(pri_peak) can be programmably set by defibrillator controller 202. Inthe illustrated embodiment, this is accomplished by maximum transformercurrent control circuit 326 which is an RC circuit having a variableresistor 327. The resistance of the variable resistor 327 is set bydefibrillator controller 202, which thereby sets the value of maximumcurrent control pin RBG on capacitor controller 322.

In practice, the transitory electrical energy store 305 cooperates withaspects of the flyback converter control to provide the desired currentregulating functionality (e.g., to keep drawing current suitable for usein charging the discharge capacitor—preferably at a level relativelyclose to a designated current draw—even while the primary coil of theflyback converter is turned off, to prevent the current drawn from themobile device from exceeding a specified limit).

With the illustrated circuitry, the draw current from the mobile devicewill be affected by several factors including the maximum primary coilcurrent I_(pri_peak), the present voltage of the capacitor 209, and thestructure of the transitory electrical energy store 305. For any givencapacitor charge level (and with all other factors being fixed), settingthe maximum primary coil current I_(pri_peak), in the illustratedcircuitry will cause a predictable current (I_(draw)) to be drawn fromthe mobile device. Therefore, for any given state, setting the maximumprimary coil current I_(pri_peak) has the effect of setting the maximumdraw current (I_(draw)) and programmably controlling the maximum primarycoil current I_(pri_peak) has the effect of programmably controllingmaximum draw current (I_(draw)).

In general, for a given maximum primary coil current I_(pri_peak), theaverage current drawn by the flyback converter will decrease as thevoltage level of discharge capacitor 209 increases during charging.Therefore, if the maximum primary coil current I_(pri_peak) ismaintained at a fixed level, the draw current will decrease somewhat ina predictable manner as the capacitor charges. In some embodiments, thedefibrillator controller 202 is arranged to occasionally adjust themaximum primary coil current I_(pri_peak) as the capacitor charges in amanner that maintains the draw current at close to the designatedmaximum allowable draw current. In a simple implementation, a lookuptable or other suitable data structure may be used to identify theappropriate values for the variable resistor 327 at different chargelevels and the defibrillator controller can occasionally directadjustment of the variable resistor in a manner that maintains close tothe desired draw current. Of course, in other implementations, thespecific parameter settings that are adjusted and/or the data structuresor algorithms used to determine the desired settings may be varied asappropriate for such embodiments. By adjusting the charging parametersas the discharge capacitor 209 charges, the discharge capacitor can becharged more rapidly without exceeding the maximum allowable drawcurrent.

In the illustrated embodiment, the transitory electrical energy store305 includes two capacitors 306, 307 which have significantly differentcapacitances, although it should be appreciated that three or morestacked capacitors may be used in other embodiments. Typically thecapacitors will have significantly different capacitances and are sizedbased on the needs of the flyback converter so that the stack as a wholecan quickly and effectively respond to switching demand—storingelectrical energy at a rate sufficient to keep drawing current from themobile device at near the desired level when the primary coil 331 offlyback converter 320 is turned off and delivering stored energy to theprimary coil (together with the draw current) when the primary coil isturned on.

In general, the number of capacitors used in the capacitor stack and theoptimal capacitance values for the individual capacitors in thecapacitor stack will vary based the nature of the flyback converter, theexpected charging range of the capacitor and other design requirements.By way of example, in one specific application, a pair of capacitorshaving capacitances of approximately an order of magnitude difference(as for example, 4.7 μF and a 47 μF) are used in the capacitorstack—although again it should be appreciated that the optimal valuesfor the capacitors may vary widely. Notably, the optimal capacitancecharacteristics of the transitory electrical energy store may vary basedon factors such as the maximum primary coil current I_(pri_peak) and thevoltage level of the discharge capacitor and therefore a variety ofdesign choices may be made in the design of the transitory electricalenergy store 305.

Although a capacitor stack is illustrated in FIGS. 5A and 5B, in otherembodiments the transitory electrical energy store may utilize one ormore inductors with one or more capacitors (one example of which isshown in the digitally controlled current limiting Buck Converter ofFIG. 3) or a wide variety of other electrical circuits may be utilizedto form the transitory electrical energy store.

In many implementations the capacitors and/or inductors used in thetransitory electrical energy store will be fixed and chosen based onoverall design goals. However, in other implementations, the transitoryelectrical energy store 305 may have programmably variable capacitanceand/or inductance characteristics. This can be accomplished, forexample, by providing a bank of capacitors and a switching structurethat allows individual capacitors to be selectively included or excludedfrom the active capacitor stack to thereby allow the capacitance of thetransitory electrical energy store to be programmably varied. Thisarrangement has the advantage of allowing the capacitancecharacteristics of the transitory electrical energy store 305 to bevaried based on factors such as the current delivery capabilities of themobile device (power supply) the maximum primary coil currentI_(pri_peak) and the then current voltage level of the dischargecapacitor. With this arrangement, the capacitance characteristics of thetransitory electrical energy store can be programmed before chargingbegins and updated as desired during charging to facilitate moreefficient charging of the discharge capacitor 209. Of course, in otherembodiments, the inductance of a component or both capacitance andinductance may be programmatically changed during charging todynamically tune the charging circuit in a manner that improves chargingefficiency.

FIG. 5B is a schematic diagram that illustrates an AED electronicsarchitecture that utilizes the valley switching flyback converter ofFIG. 5A. In this embodiment a smart phone or other mobilecomputing/communication device 105 is arranged to be coupled todefibrillator unit 110. In some embodiments, the smart phone may becoupled to the defibrillator unit using a removable connector cable suchas a USB cable, a lightning connector cable or any other suitableremovable plug in type cabling. In other embodiments, the mobile device105 may be coupled to the defibrillator using more permanent wiring. Instill other embodiments, the mobile device may be coupled to thedefibrillator wirelessly—as for example using a short range wirelesscommunication protocol for communications and inductive charging tofacilitate the transfer of energy to the defibrillator unit tofacilitate charging the discharge capacitor.

The defibrillator unit 110 includes defibrillator controller 202. Powerreceived from the mobile device 105 powers the capacitor chargingcircuitry 300 which charges the main energy storage (discharge)capacitor 209. The capacitor charging circuitry in this embodimentincludes transitory energy store 305, snubber 310, and transformer 330.The transformer is used in the valley detection flyback converter, whichalso includes valley detection switching controller 322, switch 324, andmaximum transformer current control circuit 326. In some embodiments,the valley detection flyback converter may be a quasi-resonant flybackconverter. A voltage sensor 340 is arranged to read the voltage of mainenergy storage capacitor 209 and provide that reading to defibrillatorcontroller 202. Protective diodes 341 may be used to prevent currentfrom flowing backwards from the capacitor 209 through the transformer330.

The discharge circuitry includes H-bridge 220 along with the drivers 221that drive the H-bridge switches. The drivers 221 are directed bydefibrillator controller 202. The H-bridge 220 outputs a biphasic (orother multi-phasic) shock to patient electrode pads 116 through relays229. The relays 229 are configured to switch between an ECG detectionmode in which the patient electrode pads 116 are coupled to the ECGsensing circuitry 225, and a shock delivery mode in which the patientelectrode pads 116 are connected to H-Bridge 220 to facilitate deliveryof a defibrillation shock to the patient. Although specific componentsare represented in FIG. 5B, it should be appreciated that theirrespective functionalities may be provided by a variety of othercircuits.

Referring next to FIG. 9, a variety of methods suitable for controllingthe charging of the discharge capacitor 209 will be described.Initially, when a decision is made to initiate charging (step 501), thedefibrillator controller 202 determines the maximum draw current that isavailable from the power supply (step 503). The decision to initiatecharging can be made in a variety of ways. In general, it is desirableto automatically begin charging any time that it is likely that thedefibrillator unit 110 may be utilized in an emergency situation. Thiscan take the form of initiating charging as soon as the defibrillatorunit is activated in a manner that suggests it might be used.

In some embodiments, charging automatically begins when a mobile deviceis initially connected to the defibrillator unit 110. This approach isparticularly appropriate for stand-alone defibrillator units where auser is expected to plug the defibrillator unit into a mobile phone orother mobile device to facilitate use. In other embodiments, launching adefibrillation app, or a user inputted indication of an emergency or adesire to turn on, use or charge the defibrillator may initiate thecharging. In still other embodiments, physical actions such as removingan end cap, or cover, pulling a tab or pressing a button can be used toinitiate the charging. These latter approaches are particularlyappropriate in embodiments in which a mobile device is already connectedto the defibrillator unit 110 (as may occur when a mobile device ispackaged together with the defibrillator unit, during training, or avariety of other circumstances) and in conjunction with the charging ofthe shock delivery capacitors in the context of more conventionaldefibrillator designs.

In some specific embodiments, the charging automatically begins when thedefibrillator is initially activated or powered-on. Such activation cantake a based on a manual input such as pressing an “on” or “activate”button, flipping an on/off switch to the “on” state, turning on a mobilecommunication device that is packaged as a part of the defibrillator(e.g., by pressing a home button or performing a gesture that activatesthe mobile communication device from a sleep, standby or otherwise lowactivity mode), removing an end cap or cover, pulling a tab or in othersuitable manners. In such embodiments, the charging automatically beginswhen the user first does something that shows that they want to use thedefibrillator rather than waiting to charge the capacitors until ashockable rhythm has been detected or a decision is made that deliveringa shock is appropriate.

Charging (recharging) this discharge capacitor will also generally beautomatically initiated after any discharge occurs. Of course, chargingmay be initiated in a variety of other circumstance, as for example aspart of a testing protocol or in other appropriate circumstances.

In some embodiments, an app 108 on the mobile device is launchedautomatically when the defibrillator unit 110 is initially connected toa mobile device, and/or the app begins its initial communications withthe defibrillator unit upon such connection. In other embodiments, theapp is pre-loaded on the mobile device and launched upon a physicaltrigger from the defibrillator unit 110, such as a cover tab or end capbeing removed. In still other embodiments, the app may launch on auser's phone when the phone detects that it is close to thedefibrillator (e.g., using near field wireless communication or otherappropriate technologies).

The app may be configured to automatically inform the defibrillatorcontroller 202 of the current delivery capabilities of the connectedmobile device as part of those initial communications. Alternatively,the app may inform the defibrillator controller 202 of the make andmodel of the connected mobile device, the type of connector used, and/orprovide other appropriate identifying information, such that thedefibrillator may utilize a lookup table or other suitable datastructure on the defibrillator itself to determine the current deliverycapabilities of the connected device based on such information. In otherembodiments, the defibrillator controller 202 may send a request to theapp or other suitable component of the mobile device requesting anidentification of the device's current delivery capabilities, orrequesting information such as the connector type in use, the make andmodel of the connected mobile device or other information that issuitable for determining the device's current delivery capabilities.

In still other embodiments, the defibrillator controller may be arrangedto set the current draw at a designated default rate (e.g., just under500 mA) when first activated and then communicate with the mobile deviceto determine its current delivery capabilities. If a higher currentoutput is supported by the connected device, the current draw can thenbe adjusted to the higher rate. Regardless of the approach used, thedefibrillator controller 202 determines the current deliverycapabilities of the connected device as represented by step 503.

If the defibrillator controller is unable to determine the currentdelivery capabilities of the connected device for any reason, then adefault value may be used. Typically, the default value would be thelowest current delivery capability that could reasonably be expected tosupplied by the mobile device. By way of example, when USB-2.0connectors are supported, the default may be set at 500 mA or a valueslightly less than that, e.g., 490 mA. When only USB-3.0 or moreadvanced connectors are supported, then the default may be set at 900 mAor a value slightly less than that (e.g., 890 mA). Of course otherdefaults can be used as appropriate for any particular implementation.

In some embodiments, a dedicated mobile device may be provided togetherwith the defibrillator unit. In such embodiments, the device's currentdelivery capabilities would be known and there would be no need tointerrogate the device to determine its current delivery capability.

When the maximum draw current is known, defibrillator controller 202configures the charging circuit so that the charging circuit drawscurrent from the power supply (e.g., the mobile device) at a rate thatis close to, but does not exceed the maximum draw current as illustratedby step 505. In the embodiment of FIG. 5A, this is accomplished bysetting the value of variable resistor 327, which sets the maximumprimary coil current I_(pri_peak)—which in the context of theillustrated design, effectively dictates (sets) the draw current giventhat the other components are generally fixed. However, it should beappreciated that in other embodiments, the draw current may be set in avariety of different ways. For example, as suggested above, if thecapacitance characteristics of the transitory electrical energy store305 are not fixed, its capacitance characteristics can be set as desiredbased on the state of the other components (e.g., the maximum primarycoil current I_(pri_peak) and/or the current charge status of thecapacitor 209).

Once the draw current is set, charging begins and the defibrillatorcontroller monitors the charge level of the discharge capacitor (step507). In the embodiment of FIG. 5A, the voltage sensor 340 monitors thevoltage stored in the capacitor which provides an indication of itscharge level. The detected voltage level is sent to the defibrillatorcontroller 202.

In some embodiments, the current drawn from the mobile device (or otherpower supply) may tend to vary as the capacitor charges. In suchembodiments, it may be desirable to adjust the charging parametersappropriately during the charging so that the charging circuit continuesto draw current at close to the maximum allowable draw current asrepresented by optional step 509—which helps speed the charging processwithout causing the mobile device to cut power to the defibrillator.

For example, in the embodiment of FIG. 5A, if the maximum primary coilcurrent I_(pri_peak) is maintained at a fixed level, the draw currentwill decrease somewhat in a predictable manner as the capacitor charges.Therefore, the defibrillator controller 202 may be arranged tooccasionally adjust the maximum primary coil current I_(pri_peak) as thecapacitor charges in a manner that maintains the draw current at closeto the designated maximum allowable draw current. In a simpleimplementation, a lookup table or other suitable data structure may beused to identify the appropriate values for the variable resistor 327 atdifferent charge levels and the defibrillator controller canoccasionally direct adjustment of the variable resistor in a manner thatmaintains close to the desired draw current. Of course, in otherimplementations, the specific parameter settings that are adjustedand/or the data structures or algorithms used to determine the desiredsettings may be varied as appropriate for such embodiments. By adjustingthe charging parameters during the charging cycle, the dischargecapacitor can be charged more rapidly without exceeding the maximumallowable draw current. For example, when the transitory electricalenergy store has programmable capacitance characteristics, suchcapacitance characteristics may be adjusted during charging as well.

In general, charging continues until the desired charge level isattained as represented by decision box 511. When the desired charginglevel is attained, the charging is stopped (step 513) and the app isinformed that the discharge capacitor is charged and available todeliver a shock if needed (step 515). At that point, charging can bediscontinued until a new command is received to charge (or increase thecharge of) the discharge capacitor 209.

In the embodiment illustrated in FIG. 5A, the flyback converter 320 hasa single stage which boosts the 5V input voltage suitably for chargingthe discharge capacitor to the desired discharge voltage level(typically at least 1400 to 2000 volts). In other embodiments, multiplestage flyback converters may be used. For example, in a two stageflyback converter, a first stage may be used to boost the voltage fromthe input voltage (e.g. 5V or lower when applicable) to 12 volts (whichis a common input voltage for defibrillators) and a second stage can beused to boost the voltage from approximately 12 volts to a levelsuitable for charging the discharge capacitor 209 to its desiredoperational voltage level. When desired, more than two stages can beused in a multi-stage flyback converters (or any other multi-stagevoltage booster), and the specific intermediate voltage level(s) can bewidely varied in accordance with design preferences.

In still other embodiments, different types of voltage boosters may beutilized in combination. For example, a DC-DC boost converter may beused in series with a flyback converter. In one specific example, aDC-DC boost converter may be use to boost the 5V input to 12V with the12V input being fed to a flyback converter (which may have one ormultiple stages) that boosts the voltage to the desired operationalvoltage for the discharge capacitor 209. In still other embodiments,other types of voltage boosters may be used alone or in combination withboost converters and/or flyback converters and the specific operationalvoltages of each voltage boosting component/stage may vary widely.

Some of the primary described embodiments contemplate the use of anindependent mobile device as the power supply for a defibrillator unit.However, it should be appreciated that many of the features of thedescribed flyback converters and other aspects of the describedcapacitor charging circuits may be utilized in a wide variety ofdifferent defibrillator applications. By way of example, they may beused in conjunction with defibrillators having a dedicated mobile devicepackaged together therewith in a defibrillator housing (some examples ofwhich are illustrated in FIGS. 16-18) that serves as the power supply;they may be used in conjunctions with defibrillators that obtain theirpower from external power supplies other than a mobile communicationdevice; they may be used in conjunction with more standard defibrillatordesigns which have an integrated battery that is used to supply thepower required to charge the shock delivery capacitor(s) and/or andintegrated user interface; and they may be used in conjunction with avariety of other defibrillator designs, including manual defibrillators,wearable defibrillator, implantable defibrillators, etc. For example,the described valley switching aspects of the flyback converter may beincorporated into any defibrillator design that includes a flybackconverter. Similarly, the variable maximum transformer primary coilcurrent control approach, and/or updating the maximum primary coilcurrent based on the capacitor's charge level can be incorporated intoany defibrillator design that includes a transformer.

Discharge Circuit

The discharge capacitor 209 is coupled to a discharge circuit 220 thatcontrols the delivery of a defibrillation shock. The defibrillator maybe designed to deliver a monophasic shock, a biphasic shock or othermulti-phasic shock or any other suitable waveform. As will beappreciated by those familiar with the art, biphasic shocks arecurrently preferred for medical reasons. Another advantage of biphasicshock delivery is that biphasic shock protocols typically require thedelivery of less shock energy than monophasic shock protocols.

One suitable biphasic shock delivery circuit 220 is illustrated in FIG.10. The illustrated embodiment utilizes an H-bridge 220 dischargecontrol circuit with high and low side drivers 221, so that the highvoltage line can feed to either of the two AED pads 116 (this is whatmakes it biphasic). The activation, timing and safety checks of thedischarge circuit 220 are controlled by defibrillation controller 202.

For a monophasic shock, an inductor/flyback diode (not shown) may beprovided as the discharge control circuit 220 to make the capacitordischarge last 10-12 ms.

Of course the nature of the discharge circuit 220 can be varied todeliver any desired shock profile. When desired, more complex shockdelivery circuitry may be utilized to provide greater control of thewaveform of the delivered shock.

ECG Sensing

ECG sensing/filtering circuit 225 senses electrical activity of thepatient's heart when the pads are attached to a patient. The filteredsignal is then passed to defibrillator controller 202, which passes thesignals on to the app 108 for analysis to determine whether the detectedcardiac rhythm indicates a condition that is a candidate to be treatedby the administration of an electrical shock (i.e., whether the rhythmis a shockable rhythm) and the nature of the recommended shock. The appthen instructs the controller 202 when to deliver a shock and the natureof the desired shock. In alternative embodiments, the controller 202 cando the analysis of the ECG signals.

Offloading the ECG analysis to the mobile device 105 has severalpotential advantages. Initially, it simplifies the design of thedefibrillator electronics and reduces the processing requirements oncontroller 202. Since the CPUs on conventional smart phones and tabletcomputers are quite powerful, they are very well suited for handling theECG analysis. Furthermore, the ECG processing algorithms can readily beupdated when appropriate using standard app updating protocols. Stillfurther, the fact that the detected ECG rhythms and diagnoses arepresent on the mobile device make it very easy to share that informationwith first responders on site at the time of an incident or to transmitthat information to medical personnel either during the incident (e.g.in a telemedicine setting) or after the incident. In defibrillators thathave a manual operation mode, the ECG rhythms and shock history can bedisplayed to the EMT or other medical personnel to support the manualoperation mode. When proper medical information handling procedures arefollowed, the ECGs and the shock history can also be shared withresearchers to support medical research.

Since both the high voltage shock delivery and the low voltage ECGsensing require use of the defibrillator pads 116, both the dischargecircuit and the ECG sensing circuit 225 are electrically coupled to thedefibrillator pads 166 through relay(s) 229 which facilitates switchingthe pads 116 from the low voltage system (ECG reading) to the highvoltage system (discharge). In the illustrated biphasic shock deliversystem, each pad 116 may have an associated relay 229. The state of therelay(s) is/are controlled by controller 202. In the default state, thepads are preferably connected to a filtering ECG sensing/filteringcircuit 225 (i.e., to the low voltage system) so that the patient's ECGcan be read as soon as the pads are attached to the patient and at othertimes in the process, and so that in the event of a power failure, therelays default to a low voltage system for safety reasons. When deliveryof a shock is desired, the controller 202 directs the relay(s) to switchto the high voltage discharge circuit 220. Once the relays are switched,the shock can be delivered. After the shock is delivered, the relay ispreferably switched back to the low voltage (ECG sensing) system so thatthe patient's heart's response to the shock can be evaluated and the appcan determine whether any additional shocks are advised.

In some embodiments, separate circuit boards are provided for the highand low voltage electrical systems. Although such a division ofcomponents is optional, it helps protect the sensitive low voltageelectronics from the high currents and fields associated with the highvoltage components and can help simplify any required or desiredshielding. In a specific embodiment discussed below, the boards arelongitudinally stacked within a housing 120 with the low voltage circuitboard being located closer to the electrical connector compartment ofhousing 120 and the high voltage circuit board being located closer tothe pad compartment. This allows for very efficient packaging in thehousing, helps for shielding (preventing the low voltage electronicsfrom being adversely affected by close proximity to high voltagetraces), and helps with modularity in the electronics design. Becausetwo end caps are provided (one for the connector cable and one for thepads), the low voltage components can very clearly be separated from thehigh voltage components. Low voltage components are on the connectorcable side of the housing, whereas the high voltage components includingthe high voltage circuit board and the capacitor (which is the biggestvolumetric component) and the pads are housed in the opposite side ofthe casing.

In one particular embodiment, the low voltage circuit board includesmicroprocessor 202, the current limiting circuit 205 and the ECGsensing/filtering circuit 225. The high voltage circuit board includesvoltage booster 207, discharge control circuitry 220 and relays 229 andis coupled to capacitor 209. In other embodiments, all of the electricalcomponents can be installed on a single board or packaged in a varietyof other suitable manners.

Use of Additional Power Sources

In the embodiments described above, a single mobile device is used toprovide the power to charge the discharge capacitor 209. It will beappreciated that the speed at which the discharge capacitor can becharged will be limited in significant part by the current deliverylimitations of the mobile communication device that provides power tothe defibrillator. This is due, in part, to the fact that most mobilecommunication devices and/or connector protocols impose limits on thecurrent that can be drawn from the device. In some alternativeembodiments, multiple power supplying devices can be used in parallel tocharge the discharge capacitor 209. The other power supplying device(s)can be other mobile device(s) (e.g., mobile phones or tablet computers)or can be dedicated power supplies such as USB compatible power packs,power banks and battery packs that are becoming increasingly popular forusage as cell phone backup power accessories. In circumstances in whichmultiple mobile communication devices are connected, only one of themobile communication devices would typically be used for controlpurposes, with the other essentially being utilized as additional powersupplies.

An advantage of utilizing parallel devices as power supplies is that itcan significantly reduce the time required to charge the dischargecapacitor. By way of example, using two mobile devices in parallel aspower supplies can cut the time required to charge the dischargecapacitor 209 to any particular level nearly in half. To accommodate theuse of multiple power supplies, more than one (as for example 2 or 3)connector cables 113 or a dongle type connector cable with multipledifferent source connector ends can be provided. With these arrangement,if multiple people are around at the time the defibrillator is used, anyextra available phones or other suitable power supplies can be connectedto speed the charging. An additional benefit is that if a large numberof shocks are required for any reason, the battery capacity of theprimary connected mobile device is less likely to become a limitingfactor.

To that end, it is understood that portable AEDs are typically expectedto have sufficient battery power to deliver multiple defibrillationshocks (which would often—but not necessarily always—be delivered at twominutes intervals at sequentially increasing intensities). Someregulatory standards suggest the ability to deliver on the order of 15or more shocks. In practice, it is relatively rare that more than 5 or 6shocks would be applied in any one incident and four or less shocks isunderstood to be most common. Most cellular smart phones (and othersuitable mobile communication devices) are capable of supplying suchenergy levels without excessively draining their batteries. For example,in practice, charging the defibrillator for one 150J discharge tends todrain under 2% of the charge from most currently popular smart phones.Therefore, most cellular smart phones would be able to deliver theelectrical energy required to provide a number of shocks. The ability todeliver numerous shocks can be even further enhanced by embodiments thathave the ability to simultaneously obtain power from more than onesource.

While it is contemplated that multiple mobile communication devices maybe used to speed the charging, it should be appreciated that some peoplecarry spare power supplies or various other electronic devices that maybe capable of delivering power through standard electrical cables suchas various USB cables, microUSB cables, lightning cables, etc. To theextent that any such devices are available at the time of use, they canbe used as supplemental power to speed the charging process whenmultiple connector cables 113 are provided. Any connected device thathas the appropriate processing power (as for example other mobilecommunication devices, notebook computers, etc.) can also assist with orperform any of the required processing or control.

The defibrillator unit 110 is also preferably configured so that theconnected mobile device can be swapped out in the middle of a treatmentif necessary. This can be desirable in the event that the initial phoneused had a low charge level and can no longer be used for charging. Inorder to facilitate switching of the connected mobile device, thecontroller 202 can optionally be configured to store the currentdefibrillator state and to inform a newly connected device of that state(including any diagnoses that have been made by the preceding device)when the new device is connected. In this manner, the second connecteddevice can pick up where the first one left off. In other embodiments,such information can be transferred wirelessly between the devices(using, for example, Near-field communications (NFC), Bluetooth, orshort distance wireless communication protocol. In still otherembodiments, such information can be transmitted from the first deviceto the cloud and from the cloud to the second device to accomplish thesame function. Alternatively, the newly connected device can veryquickly go through a series of status checks itself to determine thecurrent state of the event—again appearing to pick up where the firstdevice left off.

In yet other embodiments, the defibrillator unit 110 may include arelatively small battery or supercapacitor that can be used tosupplement power provided by the mobile device—or vice versa, the mobiledevice can supplement the power of the on-board energy storage device.In some embodiments, the supplemental power supply is rechargeable sothat it can be recharged if its charge drains somewhat after prolongedstorage. A potential advantage of providing such a supplemental powersupply is that it can be used in parallel with power from the connectedmobile device to speed the charge time. In some applications this may bedesirable particularly in connection with the initial charging of thedischarge capacitor. This is because the initial charge is typically themost time critical shock, because it may be desirable to deliver thefirst shock shortly after it is determined that the patient has ashockable heart rhythm. Most shock protocols contemplate a relativelyextended period between shocks (e.g. 2 minutes) in circumstances inwhich subsequent shocks are required—which provides plenty of time torecharge the discharge capacitor.

When the defibrillator has supplemental power a variety of differentpower management schemes can be used based on the relative charge levelsof the mobile device vs. the supplemental power supply. For example, insome applications, the defibrillator controller 202 or the app 108 cancheck the charge level of the mobile device by simply requesting thecharge level. If the battery on the mobile device is low, power can bedrawn solely from the supplemental power supply. Similarly, if a cellphone is incapable of delivering power for any reason, the power tocharge the defibrillator can again be drawn from the supplemental powersupply. Alternatively, if both the supplemental power supply and theconnected mobile device have a high battery charge level, power can bedrawn from both to speed the charge. If the supplemental power supply islow for any reason, then power can be drawn exclusively or primarilyfrom the connected mobile device—and if desired, power from the mobiledevice can further be used to charge the supplemental battery in timeswhen its power is not needed to charge the discharge capacitor.

Alternative Capacitor Configurations

In most of the embodiments described above, a single discharge capacitor209 is typically used. However, in other embodiments, multiple dischargecapacitors may be used with minimal changes to the other circuitry. Forexample, in some embodiments, a plurality of lower voltage capacitors,may be arranged in parallel for charging and then switched to bearranged in series for discharge. For example, a group of four or five600 volt capacitors may be arranged to be charged in parallel, and thenswitched to an electrical series configuration after the charging iscomplete to facilitate a higher voltage discharge. An advantage of thisapproach is that charging at lower voltages tends to be more efficientso that the charging occurs more rapidly. A disadvantage of thisapproach is the more extensive switching and discharge control isrequired.

In another embodiment, a plurality of lower voltage capacitors may bearranged in series or arranged in parallel for both charging anddischarging. For example, a group of four or five 600 V capacitors maybe arranged in series. An advantage of this approach is possible costand size savings that may be achievable with lower energy capacitors.

In another embodiment, a pair of capacitors or capacitor units havingopposite polarities may each be charged to a level suitable fordelivering half the total shock energy requirements. One of thecapacitors is configured to discharge through a first one of thedefibrillator pads and the other is configured to discharge through asecond defibrillator pad. In yet another alternative, two capacitorshaving opposite polarity can be configured to discharge through the samedefibrillator pad, with the other defibrillator pad always being tied toground. With this arrangement, current flows from the positively chargedcapacitor to the grounded defibrillation pad to form the first phase ofa biphasic waveform when the first capacitor is discharged, and currentflows from the grounded defibrillation pad to the negatively chargedcapacitor to form the second phase of a biphasic waveform when thesecond capacitor is discharged.

These arrangements have the potential to provide a biphasic shock thathas a somewhat different waveform than conventional biphasic shocks. Forexample, as best seen in FIG. 11A, each phase has approximately the sameenergy level and the waveforms have the same magnitude but oppositepolarities. This differs from conventional biphasic shocks in which thefirst phase tends to be delivered at a much higher voltage than thesecond phase—as seen, for example, if FIG. 11B which illustratesrepresentative biphasic 150J waveforms at three different patientresistance values.

In other implementations, the opposite polarity capacitors can becharged to different voltage levels and/or can be different sizes tofacilitate further control of the energy dispatched during each phase.This gives even greater control of the nature of the different phases.For example, one of the capacitors can be charged to first level (e.g.,1200 volts) while the other is charged to a second level (e.g. 1000volts) to facilitate biphasic shocks in which one of the phasesdischarges more energy than the other. The defibrillator controller 202has complete control of which capacitor is charged to which level andthe order in which the capacitors are discharged. Thus, the highervoltage capacitor can be discharged as either the first or second phaseof the biphasic shock.

FIG. 12 illustrates a representative discharge circuit that may be usedto discharge a pair of capacitors 1209(a) and 1209(b) in oppositepolarity. In this embodiment, the capacitors 1209(a) and 1209(b) arecharged in parallel. To facilitate charging, a charging control switch1222 is turned on by controller 202. This allows the capacitors 1209(a)and 1209(b) to be charged in parallel by the capacitor chargingcircuitry (such as any of the charging circuitry described above). Oncethe capacitors are charged, the charging is disabled by the controller202 so that charging no longer occurs, and switch 1222 is turned off.When switch 1222 is turned off, the capacitors 1209(a) and 1209(b) areelectrically isolated from one another which allows the capacitors to bedischarged separately.

In the embodiment illustrated in FIG. 12, the discharge circuit iscomposed primarily of a set of four switches 1223(a)-(d) which arecontrolled by defibrillator controller 202. The positive sides ofcapacitors 1209(a) and 1209(b) are respectively coupled to differentswitches 1223(a) and 1223(b). Switches 1223(a) and 1223(b), in turn, areconnected to relays 1229(a) and 1229(b), which, are each connected to anassociated one of the defibrillator pad 1216(a), 1216(b). The groundsides of capacitors 1209(a) and 1209(b) are also connected to therelays, with the ground side of capacitor 1209(a) being connected torelay 1229(b) through a third switch 1223(c) and the ground side ofcapacitor 1209(b) being connected to relay 1229(a) through a fourthswitch 1223(d). With this arrangement, a first phase of a defibrillationshock may be delivered by turning on switches 1223(b) and 1223(d) whenthe relays 1229(a) and 1229(b) are in discharge mode (i.e., switched tothe discharge circuit). This causes high voltage current to flow fromcapacitor 1209(b) through switch 1223(b) and relay 1229(b) to pad1216(b). In this state, the other defibrillator pad 1216(a) is connectedto the ground through switch 1223(d). This discharge can be terminatedat any time by turning switch 1223(b) off. After the first phase hasbeen terminated, an opposite polarity shock phase can be delivered byturning on switch 1223(c) (which connects pad 1216(b) to ground),turning switch 1223(d) off (which disconnects pad 1216(a) from ground)and thereafter turning on switch 1223(a) (which connects pad 1216(a) tothe high voltage side of capacitor 1209(a)). With this arrangement, highvoltage current flows from capacitor 1209(a) through switch 1223(a) andrelay 1229(a) to pad 1216(a). The opposite polarity shock phase can beterminated at any time by turning switches 1223(a) back off. The on/offstate of the various switches 1223 may be set by the defibrillatorcontroller 202—although it should be appreciated that a separatedischarge controller may be used in other embodiments.

With the described arrangement, a controlled biphasic shock can readilybe delivered by turning the switches on and off appropriately. It shouldalso be apparent that additional multi-phasic shocks having more thantwo phases can readily be provided using the same approach by simplyturning the various switches 1223(a-d) back on and off appropriately. Itshould be noted that the discharge circuitry for this embodiment issimplified relative to the discharge circuitry used to deliver abiphasic shock waveform using an H-Bridge structure—with the switchingcontrol being simple enough that it can readily be controlled by thedefibrillator controller 202 without requiring a separate dischargecontroller (although a separate discharge controller may be utilizedwhen desired).

The switches 1222 and 1223 are preferably power switches capable ofhandling the high voltage/high power shock surges associated with thedelivery of a defibrillation shock. By way of example power field effecttransistors (FETs such as those shown in FIG. 12) or insulated-gatebipolar transistors (IGBTs) work well, although other switchingstructures may be used in other embodiments.

Dynamic Discharge Impedance Detection

As is well understood in the art, different patients have differentimpedances in general, and the resistance/impedance observed between thedefibrillation pads will vary based on pad placement as well. Therefore,many defibrillators measure the actual resistance or impedance betweenthe pads prior to delivering a shock and then adjust selected shockdelivery parameters accordingly to ensure that an acceptable shockwaveform is delivered. For example, in the context of the delivery of abiphasic shock, when the patient resistance/impedance is known prior todelivering a shock, the discharge period for the first and second phases(sometimes referred to as the first and second pulses of thedefibrillation shock) may be adjusted prior to delivering the shock sothat each of the shock waveform phases imparts a desired energy level.By way of example, FIG. 11B illustrates potential target waveforms fordelivering a 150 Joule biphasic shock in patients having 50, 75 and 100ohm resistances respectively between the pads. The amount of energydelivered in the first phase of each shock is the same in each case.Similarly, the amount of energy delivered in the second phase of eachshock is the same in each case. As can be seen, the discharge periodsare different with the discharge periods generally being longer (and theshock voltages lower) for higher impedance patients. Thus, it should beapparent that when the impedance of the patient is known, the amount ofenergy delivered in each shock phase can be controlled (set) byadjusting the duration of the respective discharge periods.

Although measuring the patient resistance/impedance before commanding ashock works well, if the impedance of the shock delivery path or patientchanges for any reason after the measurement has been made, but beforethe shock is delivered (or while the shock is being delivered), theactual energy level delivered in each of the respective phases may varyfrom the target levels.

Next, an alternative approach to controlling the energy delivered duringeach phase of a biphasic shock will be described. In this embodiment,the resistance between the pads is effectively detected during thedelivery of the shock, and the period of the respective phases isdetermined “on the fly” during the shock delivery. This provides goodcontrol of the energy delivered during each phase.

In general, the discharge capacitor 209 will have a dischargecharacteristic (typically a generally exponential decay) which for anygiven charge level, varies primarily as a function of the patientresistance/impedance. The greater the patient impedance, the lower theshock current, which means that less energy is imparted by the shock ina designated period of time. For any given charge level and shockdelivery impedance (which includes the patient impedance), the resultingshock waveform can readily be modeled.

In a specific embodiment, the capacitor voltage prior to discharge isknown and the capacitor voltage is read again at a designated time aftershock delivery has begun, as for example at 2 milliseconds into theshock delivery. With the knowledge of the starting capacitor voltage andthe capacitor voltage detected at the designated mid-shock voltagereading time, the shock delivery impedance, the power delivered and thedelivery waveform can be inferred. Since the power delivery waveform canbe inferred, the period that is required to deliver any desired amountof energy can be readily determined. Therefore, if the design goal is todeliver X joules of energy during the first discharge phase of a shock,then the time at which the H-bridge should be switched to meet thatdesign goal can readily be determined based on that initial mid-shockcapacitor voltage reading. Thus, a multi-dimensional lookup table orother suitable data structure or construct can be used to correlate themid-shock voltage reading to the H-bridge switching time(s) that areappropriate for delivering the desired shock. By way of example, oneindex for the multi-dimensional lookup table can be the charge level ofthe capacitor, and a second index for the lookup table can be thevoltage detected at the designated mid-shock voltage reading. Each entryin the table can identify the switching time(s) for the H-bridge in theshock delivery circuit. That can include the timing for turning off thefirst phase, turning on the second phase, and turning off the secondphase. Of course, not all of these values are required as they canreadily be inferred based on the timing of the initial switching andother parameters values may be used to facilitate determination of thedesired switching times.

This described approach effectively allows the shock delivery impedance(which includes the patient impedance) to be determined dynamicallyduring shock delivery which allows the waveform to by adjusted on the goduring the shock. Having said that, it should be appreciated that inmany implementations it will not be necessary to explicitly determinethe shock delivery impedance. Rather, the timing of the termination ofthe first shock pulse and the timing of any following pulses in amulti-phasic shock waveform can often be determined directly withoutexplicitly calculating or otherwise determining the shock deliveryimpedance.

Effectively determining the shock delivery impedance on the fly alsoreduces or potentially eliminates the need to accurately measure thepatient impedance prior to shock delivery—and especially immediatelyprior to a shock, which can delay the shock delivery by a small amountand, as a practical matter, compensates for any impedance variationsthat could potentially occur between impedance reading and shockdelivery. In some embodiments, a patient impedance measurement that istaken prior to initiation of a defibrillation shock can be used toinitially estimate a desired shock duration/timing and the mid-shockreading can be used to update the desired shock duration/timing asappropriate.

In some embodiments, two or more sequential capacitor voltage readingsmay be made which can be used to even further improve the estimate ofthe energy delivered during each phase and the control of the timing ofthe shock phase delivery. Such readings can also be stored and used asdesired in reporting the nature of the shock delivered, etc.

The voltage sensor used for the mid-shock voltage reading can be thesame voltage sensor used to monitor the voltage level of the dischargecapacitor 209 as it is charged—e.g., voltage sensor 211 in theembodiment of FIG. 3, or the voltage sensor 340 in the embodiment ofFIG. 5A. The voltage is read by defibrillator controller 202, whichdetermines the desired H-bridge switching times and directs the internalH-Bridge switching accordingly. When shock discharge control systemsother than an H-Bridge are used, the defibrillator controller can setthe timing of the appropriate discharge switches accordingly.

Referring next to the flow chart of FIG. 19, a representative shockdischarge control approach that utilizes dynamic shock pulse timingdetermination will be described. Although not shown in the flow chart,the patient impedance may be measured pre-shock at any time after thedefibrillator pads have been attached using conventional techniques.When desired, that initial impedance measurement can be used todetermine a desired charging level for the discharge capacitor and/or toestimate a desired shock timing. In the context of a biphasic shock thatwould include the desired duration and separation of the two shockpulses that make up the distinct, opposite polarity, phases of thebiphasic shock.

Referring now to FIG. 19, when it is time to deliver the shock, theinitial voltage of the discharge capacitor is determined as representedby block 1503. The capacitor voltage (which corresponds to a particularcharge level) may be determined be reading a capacitor voltage sensor(e.g. voltage sensor 211) or in any other appropriate way. In manycircumstances, the capacitor voltage may already be known to thedefibrillator controller, which may be configured to read the capacitorvoltage on a regular periodic basis.

When conditions are appropriate, the shock is initiated as representedby block 1505. The shock may be initiated automatically by thedefibrillator controller or an app on the mobile device, or it may beinitiated in response to a shock command inputted by a user or any otherappropriate shock command In general, the pads 116 are connected to thepads in a first polarity. When a monophasic shock is delivered, a singleshock pulse is delivered with the pads connected in the first polarity.When a biphasic shock is delivered, the first phase of the shock (e.g.,the first pulse) is delivered with the pads connected in the firstpolarity and then the polarity of the connection is switched tofacilitate delivery of the second phase (e.g., the second pulse).

A short period after the discharge has begun, a then present voltage ofthe capacitor is read/measured as represented by block 1507. Typically,the time at which the capacitor voltage is read will be predetermined,as for example 2 msec after the discharge begins, although the specifictiming may vary and a fixed period is not strictly required in allimplementations. Preferably the capacitor voltage is read quickly enoughso that the capacitor won't discharge more than desired before thevoltage is read, but after enough time has elapsed to be able toaccurately predict the discharge curve.

As discussed above, this mid-discharge voltage reading is then used todetermine or update the desired shock timing as represented by block1509. When a monophasic discharge is utilized, the shock timingdetermined will include the timing at which the discharge will beterminated. When a biphasic or more extended multiphasic discharge iscontemplated, then the determined shock timing may also include thestart and stop timing for the other shock phases as well. In somecircumstances, the timing determined may actually update an estimatedtiming that is based on a pre-shock impedance measurement, a defaultshock timing or other appropriate shock timing setting. The shock timingmay be determined algorithmically, through the use of look-up tables orother suitable data structures or using any other appropriate approach.

In some implementations/circumstances it will be desirable to checkand/or update the shock timing multiple times during the shock deliveryas represented by optional block 1511. For example, voltage readings maybe made every 2 msec or at other appropriate intervals and the shocktiming may be verified or updated as appropriate each time that areading is made—effectively repeating steps 1507 and 1509. This can beparticularly desirable since it may be possible to better estimate thedischarge characteristics and thus the desired pulse timing later in thedischarge cycle. However, it is undesirable to wait too long to make thefirst estimate so that the first shock pulse doesn't extend longer thandesired in circumstances in which the patient impedance is relativelylow. It should be appreciated that these supplemental checks areoptional and may be eliminated in some embodiments.

With the desired shock timing known, a switch may be turned off todisconnect the defibrillator pads 116 from the discharge capacitor 209at the desired timing to complete the first shock pulse as representedby block 1513. When a biphasic shock waveform is desired, the pads maythen be electrically reconnected to the discharge capacitor after anydesired or required switching interval and the second phase initiated atthe desired timing. The pads are then electrically disconnected from thedischarge capacitor 209 when the second phase is completed.

In some embodiments it may be desirable to utilize capacitor voltagemeasurements read during the second phase of a biphasic waveform incontrol of the duration of the second phase. In such circumstances thevoltage of the capacitor may be read at specified times during deliveryof the second phase of the shock waveform and the desired pulse timingmay be updated accordingly as represented by optional block 1515 whichreturns the logic from to step 1507. Of course, the same approach can beused in the control of even further phases if a multiphasic waveformhaving more than two phases is used.

In some embodiments, separate capacitors may be used to deliver thefirst and second phases of a biphasic shock. In such embodiments, thedescribed shock pulse width control approach can be used separately inthe control of the pulses delivered by each capacitor. One suchdischarge capacitor architecture is described above with respect to FIG.10. However, it should be appreciated that the described shock pulsecontrol approach can be used in conjunction with virtually any capacitorarchitecture.

Use Scenarios

In the primary described embodiments, the defibrillator capacitor 209 ischarged from the phone when the AED is deployed. Although this isexpected to be one of the primary use scenarios, other use scenarios canbe supported as well. For example, if the user will be attending aparticular event at which they are particularly concerned about the riskof someone having a cardiac arrest incident, they could proactivelycharge the AED prior to the event. The availability of this potentialuse mode depends on the rate at which a defibrillation charge stored inhigh voltage capacitor 209 dissipates when no shock is delivered.

In practice, the AED can be configured to passively dissipate thecapacitor charge over any time period desired. In some applications, itmay be desirable to passively dissipate the charge over a relativelyshort period of several hours or less which has the potential advantageof reducing the risk of a shock being inadvertently delivered throughmisuse of the device. In other applications, the AED can be configuredto passively discharge the capacitor over a longer period such as 3-4days.

As discussed above, a capacitor voltage sensing circuit 211, 340 (suchas voltage divider) is provided to facilitate monitoring the state ofthe capacitor charge. The sensing circuit will draw a small amount ofcurrent from the capacitor and thus, when the sensing circuit isconnected to the capacitor, it provides a small drain on the capacitorcharge, thereby acting as a capacitor charge bleed circuit. The timeperiod over which the capacitor dissipates its electrical charge throughthe voltage sensing circuit can be controlled by varying the size of thevoltage sensing circuit's equivalent resistance. For example, if aseveral hundred mega-ohm resistor is used as the voltage sensing circuitresistor, the defibrillation capacitor charge will dissipate over a timeframe on the order of 3-4 days which facilitates the pre-charging usemode. If longer charge holding periods are desired, a switch (not shown)can be provided to allow controller 202 to turn off the voltage sensingcircuit 211, 340, which eliminates the voltage sensing circuit drain andprolongs the charge hold time. If shorter passive discharge periods aredesired, either a smaller voltage sensing circuit resistor can be usedor a separate discharge circuit (active or passive) may be provided.

In other embodiments, a high resistance resistor can alternatively oradditionally be provided between the leads of the capacitor to form aconstant and permanent bleed. Alternatively, a mechanism may be providedfor internally discharging a charged capacitor if a shock is notrequired after the shock discharge capacitor has been charged. Such amechanism can take the form of a power resistor or a bank of powerresistors that are designed to receive a monophasic or biphasic shock.Such a discharge mechanism can also be used for performing self-checksof the discharge functionality.

As pointed out above, one desirable way to use the defibrillator unitsdescribed above is to connect an operator's personal smart phone (orother personal mobile communication device) to the unit at the time ofan incident thereby: 1) powering the defibrillator unit from the phone;2) using an app installed on the phone as a user interface; 3) using theprocessing power of the phone to handle certain processing and controltasks associated with the use of the defibrillator; and 4) provideconnectivity that can provide a variety of support services. In otherimplementations, the integrated smart phone may be connected usingwireless inductive charging and a short range communication protocol aspreviously described.

In other applications, a custom built smart phone or other mobilecomputing device can be packaged together with the defibrillator unit sothat the operator does not have to use their own phone. This works wellbecause most smart phones today (including low cost smart phones)package a number of features that are very useful in defibrillatorcontrol and cardiac arrest incident management into a very smallpackage. For example, most smart phones have significantly moreprocessing power than conventional defibrillators. They have a highquality display and audio capabilities that can be leveraged to guide alay or minimally trained operator through an incident. They can providea user interface that potential users are very familiar with, which mayreduce a lay user's reluctance to try to operate a life saving medicaldevice that they are not particularly familiar with in an emergencysituation. They include integrated batteries that provide more thanenough power to power a defibrillator. They have built in communicationtechnologies such as cellular, Wi-Fi and Bluetooth capabilities that canbe used to facilitate a variety of response related services. They alsohave built in sensor such as audio microphones, cameras, etc. that canbe use in advantageous ways during a medical incident.

In some implementations the integrated smart phone (or tablet or othermobile device) may be permanently attached to the defibrillator housingor fixedly wired to the defibrillator unit. In other implementations,connecting cables can be provided (e.g. packaged internal to thehousing) as described in the context of defibrillators suitable for usewith an operator's personal smart phone or other mobile device.

Another feature supported by the use of a mobile device is theavailability of an established infrastructure for readily and easilyupdating software remotely. As should be apparent, the defibrillator appcan be arranged to define the amount of energy that is delivered in eachshock phase. Therefore, the nature and waveform of the shock can readilybe modified through software (app) updates to reflect the latest medicalresearch and shock protocol recommendations. This can include usingdifferent types of waveforms for different types of detected heartrhythms, using different energy discharge levels based on patientimpedance or other factors, or otherwise programmably varying the shockprofile based on general medical recommendations or medicalrecommendations based on any detected patient characteristic.

The Defibrillator Unit Housing

The defibrillator unit 110 includes a housing 120 that encases theelectrical components of the defibrillator. The housing unit may take awide variety of different forms. By way of example, U.S. ProvisionalPatent Application No. 62/433,067 filed on Dec. 12, 2016 and 62/566,896,filed Oct. 2, 2017, each of which is incorporated herein by reference inits entirety, describe some suitable housing structures.

Referring next to FIGS. 1 and 14, one particular housing embodiment willbe described. In the illustrated embodiment, housing 120 is generallytubular with a generally oval shaped cross sectional geometry. Theopposing ends of the housing 120 have large end openings 121, 122 thatare covered by associated end caps 124, 125. The oval shaped housing hastwo flat, parallel sides thereby creating a “stadium” shaped oval crosssection. This oval shaped tubular housing provides a familiar feel tousers and is easy to carry in a backpack, a sports bag, a hand bag orpurse, the glove compartment of a car or in any of a wide variety ofother manners thereby making the defibrillator unit highly portable. Theflat sides help prevent the unit from rolling.

In this embodiment, one end of the housing 120 forms a compartment thatholds the connector cable 113 that plugs into the phone. The other endforms a compartment (sometimes referred to herein as a drawer) thatholds the defibrillator pads 116. The drawer may also optionally containa small pair of scissors to assist in cutting away clothing ifnecessary, wipes, a small razor to shave off patient hair in the regionswhere defibrillator pads 116 are to be attached and/or a mouthprotection device for a user administering CPR.

The exterior of the housing 120 is screwless and completely watertight,allowing the AED to be transported, and if necessary used, in a varietyof weather conditions. Internal clipping mechanisms and o-rings are usedto secure and insulate the interior. Gaskets are used to furtherinsulate the electrical components inside when the caps are taken off.In the illustrated embodiment, the housing 120 is composed of twosections 120(a), 120(b) that snap together using clips 123.

End cap 125 has a projecting cover 126 that mates with a correspondingcutout in pad side of housing section 120(b) to provide easy access tothe defibrillator pads 116 and other components in the drawercompartment when end cap 125 is removed. The end caps 124, 125 may becolor coded which helps a user following the instructions for use removethe end cap 124 that covers the compartment that houses connector cable113 first in order to expedite the process of getting the phone pluggedin to begin capacitor charging.

The electronics mount to an internal frame (sometimes referred to as anelectronics cage or skeleton), which also serves to help join the twohalves of the exterior body together securely. The housed electronicsinclude a high voltage capacitor 209, a low voltage circuit board 237and high voltage circuit board 238. In the illustrated embodiment, theinternal frame includes three longitudinally spaced apart plates, with aplurality of beams extending between the plates to form a PCB cage and acapacitor cage respectively which are illustrated in more detail in theincorporated provisional application No. 62/433,067.

The pad side housing section 120(b) has an internal flange that servesas a stop for the internal frame. More specifically, one of the platesabuts against and is coupled to the flange 127 by appropriate fastenerssuch as screws (although clips or other fasteners may be used). Theconnector cable side housing cable has a similar flange 128 to whichplate 131 of the internal frame is attached in a similar manner Thesestructures together with clips 123 hold the electronics cage firmly inplace in the assembled product and cooperate with the cage to helpprotect the defibrillator electronics in the event of rough handling.

Each end cap may have a structure attached thereto that can readily begripped and pulled by the user to remove the cap when the AED is used.In some of the illustrated embodiments, the pull structure takes theform of a loop integrally molded into the end cap. In anotheralternative, each end cap may have a straps attached thereto. The freeend of each strap has a round tangs that serves as a pull tab that canbe pulled by the user to easily remove the respective end caps from thehousing 120. In other embodiments, a variety of other grip mechanism canbe used to make it easier for a user to remove the end caps.

The housing 120, the end caps 124, 125 and the internal structuralskeleton structure may all be fabricated from plastic which works welldue to plastic's low electrical conductivity, light weight, and ease ofmanufacturing. However, it should be appreciated that other appropriatematerials may be used for some or all of these components in otherembodiments.

In some embodiments, one end of the connector cable 113 is hard wired tothe low voltage circuit board 237. However, in other embodiments aconnector may be provided to facilitate coupling the connector cable tothe defibrillator electronics. The defibrillator pads 116 preferablyhave connectors that plug into pad connector port 156 that is mounted onthe housing 120. This allows the defibrillator pads to be readilyexchanged when appropriate, as for example every few years to ensurethat the pads are always effective, after a use, or to facilitate theuse of training pads during training. Each pad 116 preferably has anassociated wire that is long enough to permit the pads to be placed onthe patient in either (i) an across the chest configuration or (ii) afront and back configuration, as appropriate when the defibrillator isused. The use of a quick connector also allows the use of different padsfor pediatric and adult cardiac events with the user simply plugging inthe appropriate pads at the time of use.

FIGS. 15A and 15B illustrate another embodiment of an oval-shapedtubular housing 120(a). As best seen in FIG. 15A, housing 120(a) alsohas a stadium shaped oval cross section with a pair of flat sides, buthas only one end cap 124(a). In this embodiment, both the connectorcable 113 and the pads 116 are accessible through the end cap 124(a).The end cap 124(a) has a pull feature 129 that may be pulled to separatethe end cap from the housing 120(a). In the illustrated embodiment, thepull feature 129 takes the form of a loop. When desired, a pull strapmay be attached to the loop. The strap may be pulled to remove the endcap from the end of housing 120(a). In other embodiments, a variety ofdifferent pull features may be utilized in place of the describedloop/strap arrangement.

The housing 120(a) may be molded as a single piece such that it's onlyopening is the end covered by end cap 124(a). The end cap 124(a) may besealed using an o-ring (not shown). Thus, like the previously describedembodiment, the exterior of the housing 120(a) is screwless andwatertight, allowing the AED to be transported, and if necessary used,in a variety of weather conditions.

FIG. 15B is an end view of the housing 120(a) with the end cap 124(a)removed. In the illustrated embodiment, the interior of housing 120(a)includes a pads compartment 193 that houses the electrode pads 116 and acompartment 194 that houses the defibrillator electronics.

The external appearance of selected embodiments of the defibrillatorsshown in FIGS. 1 and 14-15 are illustrated U.S. Design Application No.29/626,141, which is incorporated herein by reference.

In other embodiments a single flat edge or more than two flat edges canbe provided. At least one flat edge is often desirable for a tubularhousing to prevent rolling and a single flat edge can help orient thedefibrillator.

FIGS. 16 and 17 illustrate yet another housing configuration. In thisembodiment, defibrillator unit 710 includes a dedicated smart phone 705that is integrally packaged in housing 720 such that the phone's displayscreen 706 is exposed and can be used as the display for defibrillatorunit 710. As best seen in FIG. 17, the housing 720 includes threecompartments 722, 723 and 724. Compartment 722 houses the dedicatedsmart phone 705. The smart phone has a touch screen display 406 that isexposed through an opening in compartment 722 such that the smart phonecan be operated in a generally conventional manner. Compartment 723houses the electrode pads 116. Compartment 724 houses the defibrillatorelectronics.

In the embodiment of FIGS. 16-17, the housing 720 has a “gem-shaped”cross-section with several flat sides that the defibrillator can rest onduring storage or use. In the illustrated embodiment, the housing has: afront surface 731 that exposes the display screen 706; a back surface732 that is substantially parallel to the display screen; two upper sidesurfaces 734, 735 that taper outwardly and downward from opposing sidesof the front surface; two lower side surfaces 737, 738 that taperinwardly and downward respectively from the upper side surfaces 734, 735to the back surface 732. The housing also has end walls 739 on opposingends of the housing. In the illustrated embodiment, upper side surface734 includes an opening 741 that provides access to the secondcompartment 723 to provide access to the electrode pads 116. In someembodiments, the pads opening 741 takes up substantially the entire faceof upper side surface 734. In others the opening is smaller relative tothe size of the upper side surface 734. In some embodiments the displayopening in compartment 722 takes up substantially the entire face or atthe vast majority of the face of front surface 731 such that the face ofthe front surface is only slightly larger than the face of the mobilecommunication device. In many embodiments the junctions between thevarious side surfaces are rounded to provide smooth corners. In theillustrated gem shaped embodiment, the defibrillator may be supportedfor use on any of lower side surfaces 737, 738, back surface 732 oreither end surface 739.

In the perspective view of FIG. 16, the phone is shown in place. FIG. 17shows the housing 720 itself (i.e., empty) such that the threecompartments 722, 723 and 724 can be seen. An end cap (not shown in FIG.17, but in place in FIG. 16) attaches to the open end of the housing 720to hold the components in place. Like the other embodiments, the housing720 may be sealed to be water tight.

FIG. 18 illustrates another integrated housing 720(a) that is similar tothe embodiment of FIGS. 16 and 17 with a difference being that thehousing 720(a) has a rounded bottom 723(a) rather than a flat backsurface 732. The other surfaces of housing 720(a) are similar to thefront, side and end surfaces described above with respect to FIGS.16-17. The external appearance of selected embodiments of thedefibrillators shown in FIGS. 16-18 are illustrated U.S. DesignApplication No. 29/626,256, which is incorporated herein by reference.

Although a few specific housing geometries have been shown, it should beappreciated that the described defibrillator electronics can be packagedinto a wide variety of different form factors. Conversely, the describedhousings may be used to package defibrillators having a wide variety ofdifferent capabilities.

The App and Process Control

The app 108 is installed, or installable in memory on the mobilecommunication device 105. Preferably the app is installed on the mobilecommunication device and the user practices with both the app and thedefibrillator before it becomes necessary to actually utilize thedefibrillator in a medical emergency. The app can be factory installedon the mobile communication device as part of a health related suite ofapps or can be downloaded from an appropriate app store. The app modelallows the user interface and phone based control logic to be updatedwith improvements, including any new ECG interpretation techniquesand/or recommended shock treatment practices and protocols. In stillother embodiments, the app may be loaded into memory on thedefibrillator unit 110 that is accessible by processor 202 such that itcan be automatically cross installed onto the phone (or other mobilecommunication device) when the defibrillator unit is first connected todevice 105 if no suitable app already resides on the connected device105 at the time of use.

The incorporated U.S. Provisional Patent Application No. 62/433,067includes screenshots showing a representative set of instructionsscreens that may be presented on the display of the mobile device toguide a user through the use of the AED. The instructions are believedto be self-explanatory. Of course the presentation and content of theuser instructions and user interfaces may vary significantly and theflow of the presentation may vary based on various status informationthat becomes available to the app 108 during use of the device.

Preferably any user instructions are also spoken through the phone'sspeakers in a calm and confident tone in parallel with their display onthe display screen. This allows some user to better focus on the tasksat hand rather than reading all instructions from the display screen. Italso can help calm the user down during a high stress event.

In some implementations, much of the control of the AED is performed bythe app 108, although it should be appreciated that in differentimplementations, various aspects of the AED control may be distributedbetween the app and the on-board controller 202. The overall processcontrol is generally illustrated in FIG. 13.

Initially the defibrillation unit 110 is plugged into the I/O port onphone 105 (or other mobile device) using connector cable 113. When theconnection is made, controller 202 is powered, initializes and sends amessage to the phone 105 to automatically launch app 108 if it has notalready been opened by the user. Alternatively, the user can manuallylaunch the app in a conventional manner at which point the user will beprompted to plug the connector cable 113 from the defibrillation unit110 into the phone if that hasn't already been done. Preferably bothinitiation approaches are supported so that the AED picks up immediatelyfrom the appropriate point regardless of how the user starts.

As soon as the phone is connected to the defibrillation unit, thecapacitor begins to charge with the charging being regulated by currentregulating circuit 207. The app also preferably checks to determine thecurrent level that can safely be drawn from the phone's battery forcharging. In some embodiments, the app determines and stores the maximumcurrent draw permitted by the device on which is installed at the timeof installation. If the permissible current draw is different than thedefault current draw, the app 108 may instruct the controller 202 to setthe current regulating circuit 207 to draw current at the approvedlevel.

In parallel with the capacitor charging, a check is made to determinewhether the defibrillator pads 116 have been connected to the AED. Ifnot, the user is instructed to plug the pads 116 into the defibrillationunit. It is noted that the pads wires have connectors that plug into amating connector 156 on the housing 120. Once the connection of the padshas been verified, the control routine then instructs the user to placethe defibrillation pads 116 on the patient. The fact that the pads 116have been placed on a patient can be automatically detected bymonitoring the impedance between the pads which will be lowered when thepads are attached to the patient's skin. Once the pads are attached tothe patient, the ECG signals can be analyzed to determine whether thepatient's condition is shockable or non-shockable. Any of a variety ofpublically available or proprietary QRS detection algorithms may be usedto determine the nature of the patient's heart rhythms and theappropriate shock voltage/intensity may be determined accordingly. Ifone of the pads becomes detached from the patient at any time, the usercan be warned and instructed to reattach or better attached the pad ofconcern.

If the cardiac rhythm is determined to be shockable, the control logicdetermines whether the capacitor is already charged to the desiredlevel. If not, the logic waits for the capacitor to charge to thedesired level. The app 108 can poll defibrillator controller 202 torequest the current charge or may simply request that the capacitor becharged to a desired level. If asked for the current charge, thedefibrillator controller 202 simply returns the current charge level. Ifasked to charge to at least a designated voltage threshold, thecontroller 202 monitors the charge state of the capacitor and sends amessage to the app once the desired charge is reached. Whether thecapacitor keeps charging after the designated threshold is hit dependson whether the threshold identified by the app is a minimum voltagethreshold or a maximum voltage threshold. In various embodiments, eitherthe voltage level or the amount of energy stored can be controlled. Inembodiments in which the capacitor energy storage amount and voltagelevel can be controlled somewhat independently, both types of controlmay be used.

Once it is confirmed that the capacitor has been charged appropriately,the user is informed that a shock is advised and instructed to standclear of the patient, an initiate shock button is displayed on themobile phone's screen. When the user presses the button an initiateshock command is sent from the app 108 to defibrillator controller 202,which initiates the shock. As soon as the shock is delivered, capacitorcharging resumes and the AED returns to the ECG monitoring mode. Thenewly received ECG signals are analyzed by the app and the cycle can berepeated as necessary. In parallel, the user may be instructed toperform CPR for a period of time—as for example two minutes. Similarly,if the ECG analysis determines that no shockable rhythm exists, the usermay be prompted to perform CPR if CPR is advised.

In some embodiments, the app can be configured to alert the user that itwill be delivering a discharge, and then proceed to deliver a dischargewithout user input after the user has had an opportunity to stand back.

The app may also optionally be configured to automatically contact orcall an emergency number (such as 911 or a doctor on call) when it isfirst deployed to request emergency assistance and/or to provide thefirst responders with the patient's exact GPS coordinates. The contactcan be in any desired form including text based messages, a prerecordedvoice message, a live connection or any other suitable form ofmessaging.

In some implementations the user is given an option to connect directlywith a doctor (or other emergency medical personnel) who can help themmanage the medical situation. Such a live connection can be in the formof a standard or IP based phone call, a video connection or otherappropriate mechanism. If desired, the app can have a button that can beselected by the user to initiate such a connection.

In some embodiments, the app is configured to keep a log of theactivities that occur during use. This includes persistently storing afull shock history—which may include information such as: an indicationof the number of shocks delivered; the energy delivered in each shock;and the time at which each shock was administered. Other shock relatedinformation such as the voltage or waveform utilized in each appliedshock, etc. may be provided as well if desired.

The log also records all ECG signals that were received throughout theentire period of use (regardless of whether a shock is applied) and thediagnosis made that lead to the decision regarding whether or not toinitiate a shock (e.g., the diagnosed condition is ventriculartachycardia). This event history log will typically be stored locally inthe memory of the mobile communications device—although in otherembodiments it may additionally or alternatively be stored in memory onthe defibrillator or transmitted to a remote server.

The event/shock history is preferably also made available to emergencyresponders when they first arrive at the scene. In some implementations,an icon or other GUI button (such as an “i” icon—not shown) is displayedon each user interface screen associated with the app that when pushedimmediately transitions the screen to an event history screen whichshows the medical personnel exactly what has been done with the patientup to that point and can show the first responders/medical personnel thenature of the patient's ECGs both before and after the delivery of anyshock(s). This type of immediate access to the shock history can be ofgreat use to the medical personnel in determining what actions to takenext. In such embodiments, pressing the icon from an event history ormanual operation mode can cause the defibrillator to transition back toits standard AED mode.

Since the shock history is persistently stored, it can also betransferred to or accessed by doctors treating the patients at a latertime. Such records can also be useful in studying the efficacy ofdifferent shock profiles for treating specific types of cardiac events.It should be appreciated that the shock history is medical informationand therefore, if the information is shared outside of the incidentitself, any transmission or sharing of such information should be secureand compliant with any applicable medical information handlingstandards, such as HIPAA in the United States.

In some embodiments, the app can be configured to operate thedefibrillator as either an AED or a manual defibrillator. In the manualdefibrillator mode, the operator (which should be a trained medicalpractitioner or first responder) is given more control over the natureof the shock delivery. By way of example, the operator may be allowed toset the amount of energy to be delivered by the shock, the shock voltageand/or other characteristics of the shock waveform. When the apptransitions to the manual operation mode, the event history and ECGwaveforms are preferably displayed or made available to the user asdiscussed above.

The app can also be arranged to provide the owner of the AED withimportant reminders such as alerts notifying users when they need toreplace the pads in their mobile phone powered defibrillator (pad forexample need to be replaced every few years and failure to replace thepads when advised is a source of AED malfunctions—and breakdowns duringuse). Having these alerts on the cell phone, a device which people useand check on a regular basis, increases user awareness as to the stateof their medical equipment and the kinds of action the user needs totake to keep their defibrillator in good working condition.

These notifications can be delivered to the host mobile device as usenotifications (e.g., using the notifications function on Apple andAndroid devices), and/or as SMS or other suitable messages—which areparticularly useful when the notification(s) is/are delivered to othermobile devices. The use of the host device's notification system isparticularly powerful when the host device for the app is a registereduser/owner's personal device. In embodiments in which a dedicated smartphone or the like is provided as an integrated component of thedefibrillator (as for example in the embodiments of FIGS. 16-18), thenotifications may additionally or alternatively be sent to theregistered owner/user's personal device using SMS or other suitablemessaging technologies. In still other embodiments, a message can besent to an intermediary remote server (or a functional equivalent) andthen sent from that remote server to a registered user's personaldevice.

There are a wide variety of notifications that may be provided. Forexample, low battery notifications may be provided. In the context of apersonal phone, the app can also be aware of the host mobile device'sbattery charge level such that it can alert the user when the battery isbelow recommended AED-Operating levels. In the context of embedded phonedefibrillators, the notification can be that it is time to recharge thebattery for the AED. In some embodiments, multiple level notificationscan be sent. For example, a first notification can be transmitted when acharge is recommended and a second notification can be sent when thebattery is critically low.

In many embodiments, the defibrillator is configured to periodicallyexecute self-checks to make sure that it is still in good operatingcondition. In other embodiments, the app may be configured to direct theexecution of such tests. Alert notifications may be used to inform theowner that a self-test has failed or that the defibrillator requiresattention or that it is time to plug the user's phone into thedefibrillator in order to test the defibrillator.

Another example of an alert that can be provided is a reminder to take arefresher course when a User's CPR certification has expired.

A variety of incident alerts may also be sent in the event that thedefibrillator is deployed. The incident alerts may be sent via SMSmessages or using any other suitable messaging protocol. These incidentalerts may be sent automatically in response to the user pushing an“emergency” button displayed on the user interface. The app may beconfigured to prompt a user to push the emergency button if the deviceis being deployed in a real emergency. In some embodiments, an incidentalert may be automatically sent to an emergency number (e.g., 911 in theUnited States) to initiate alerting first responders. The incident alertmay provide the recipient with a variety of different information,including the nature of the event (e.g., a potential cardiac arrest),and the location of the event (etc.)

In some embodiments, an incident alert may be sent automatically to oneor more of a registered owner of the defibrillator, a person responsiblefor the defibrillator and/or any other person that may have reason toknow that an incident is in progress. This type of alert is especiallyuseful when the defibrillator is kept in a public location—as forexample at a school, at a sports field, or in any other public space. Inone particular example, if a school has a nurse or a teacher oradministrator that is trained on use of the defibrillator, such personcan immediately be informed of the existence and location of anemergency on school premises so that they can immediately respond to theevent.

The app may also provide CPR instructions for an inexperienced user ofthe AED who doesn't know, or can use a refresher on CPR. Furthermore,using analysis algorithms on the phone, it is possible to estimatewhether or not CPR was performed on the patient, which is informationthat can be presented to the EMTs upon their arrival.

Inductive Charging

In many of the embodiments described above, a connector cable or otherwired connection is utilized to connect the defibrillator unit to themobile device. However, in other embodiments the connection can beentirely wireless. For example, it is likely that wireless charging willbecome a common feature in smart phones and other mobile communicationdevices in the near future. When a mobile device is configured tosupport wireless inductive charging, it can readily be adapted todeliver energy to peripheral devices using the same coils and circuitry.The defibrillator can readily be adapted to receive its dischargecapacitor charging power through a wireless charging interface. By wayof example, one such embodiment is illustrated in FIG. 20.

In the embodiment of FIG. 20, the defibrillator housing 460 includes amobile device receptor 461 that is configured to receives a smart phone455 having an inductive charging coil (not shown) near its back surface.The housing also includes an inductive charging coil 462 that ispositioned adjacent the location that the smart phone charging coilwould be located when placed in the receptor 461. With this arrangement,the energy for the discharge capacitor charging circuit can readily besupplied through inductive charging from the smart phone 455 or anyother suitable mobile communication device that supports inductivecharging.

Other Embodiments

Although only a few embodiments of the invention have been described indetail, it should be appreciated that the invention may be implementedin many other forms without departing from the spirit or scope of theinvention. For example, although particular logic and electroniccircuitry has been described to facilitate explanation of variousaspects of the invention, it should be appreciated that the actualelectronic circuits, algorithms and/or logic used to accomplish thedescribed functions may vary widely and are in no way intended to belimited to the accompanying diagrams, figures and flow charts. Rather,various components, steps and functions may be reordered, altered, addedor deleted in accordance with designer preferences and/or the needs ofany particular implementation.

The use of ubiquitous mobile devices such as smart phones and tabletcomputers as a power supply has the potential to facilitate reductionsin the size and cost of the described defibrillators relative to variouscommercially available defibrillator designs as well as to reduce someof the shelf life concerns of many traditional AEDs. The use of the app108 as part of the defibrillator control also allows the defibrillatordesigner to take advantage of the powerful processing power of smartphones in the analysis of the heart rhythms The flexibility afforded byusing an app to control the defibrillator also allows the ECG signalprocessing and defibrillator control logic to be readily updated toreflect the latest developments in cardiac care.

The use of a smart phone based app as the user interface also has animportant advantage of familiarity to the user. That is, since mostusers interact with apps on their phone every day, packaging the userinterface in an app makes people feel more comfortable when respondingto an emergency situation that requires use of an AED.

The app can also be configured to provide metrics related to thedefibrillators' use. This data can further be used to infer aboutgeneral AED performance, perform studies on people's reaction toemergency situation, and ultimately inform redesigns of the product.

The various control methods described herein can be implemented usingsoftware or firmware executed the defibrillator controller, an appexecuted on a smartphone or other mobile computing device and/or anyother processor suitably programmed with appropriate control algorithmsAlternatively, when desired, the functionality can be implemented in theform of programmable logic (e.g. programmable logic arrays, FPGAs, etc.)or using application specific integrated circuits (ASICs) or acombination of any of the foregoing.

When software or firmware algorithms are used, such algorithms may bestored in a suitable computer readable medium in the form of executablecomputer code(programmed instructions) with the operations being carriedout when a processor executes the computer code. The defibrillator orthe defibrillator controller may include memory suitable for storing allof the code that is to be executed by the defibrillator and the mobiledevice includes memory suitable for storing the defibrillator app and/orother software or firmware to be executed by the mobile device.

The defibrillator may also be used for training purposes. When used fortraining, the capacitor is not charged upon connection with the phone(this can be accomplished by sending a command from phone to thecontroller 202 instructing the controller 202 not to charge). In thismode the AED itself can be used in simulated emergency scenario forpractice without the user risking inadvertent discharge of thedefibrillator. During such practice, the user can practice attachingpads, performing CPR, and practice responding to an emergency cardiacarrest situation.

In the primary described embodiments, the defibrillator capacitor 209 ischarged from the phone when the AED is deployed. Although this isexpected to be a common use scenario, other use scenarios can besupported as well. For example, if the user will be attending aparticular event at which they are particularly concerned about the riskof someone having a heart-attack, they could proactively charge the AEDprior to the event. To support such a usage model, the AED can beconfigured to charge passively dissipates the capacitor charge overseveral days rather than over a shorter period of several hours or lesswhich would may optionally be provided in order to reduce the risk of anshock being inadvertently delivered.

In another use scenario, the defibrillator can include a small batterywhich serves as a supplementary power supply. The availability of thistype of supplementary power ensures that the AED can be used even if thephone is nearly fully discharged. At the same time, the phone providesan additional power supply in the event that more shocks are requiredthan can be supported by the supplementary power supply. Thesupplementary power supply may be housed in a wide variety of locationswithin the device such as in one of the compartments exposed by the endcaps. In one particular implementation, a modular battery pack can beprovided that fits into the connector cable compartment of housing 120.The module can optionally be arranged such that the phone cable can bepulled through a center section in this modular battery pack, andrepackaged on the outer side of this module. This module can further bearranged to have all the necessary control system on it to turn the AEDinto a self contained device that can operate without the phone ifnecessary. For example, the module can include the ECG processing logic,speakers for user interface, and a manual shock button for the userpush. It should be appreciated that because the supplementary battery'sdischarge rate (and the corresponding charge time) can be controlled,the supplemental battery does not have to be as large as the batteriesprovided with most AEDs.

More generally, the described mechanical design allows for modularcomponents to be readily added at the ends and integrated with the maindefibrillator circuitry and mechanical design. One such potential add-onis the supplemental battery described above. However in otherembodiments any other suitable modules could be added, including forexample a first aid supply module or compartment, etc.

Many conventional portable AEDs are placed in cabinets at public orprivate locations so that they are available in the event of anemergency. Thus, in practice they tend to sit unused for extendedperiods of time (potentially multiple years) and they are expected toperform well when needed. A problem that is sometimes encountered isthat when it comes time to use a conventional AED, its battery may havedischarged to a level that makes the AED unusable or less functionalthan desired. Such problems can be mitigated by providing such AEDs withone or more connectors that allows the AED to be coupled to a phone,tablet or other mobile communication device and supplemental capacitorcharging circuitry as described herein (e.g., a controller, currentregulating circuitry and voltage booster) to allow supplemental power tobe supplied to the AED from the phone as necessary. In still otherimplementations, conventional AEDs can be adapted to interface with thedescribed app (either through a connector cable or wirelessly) toprovide a better user interface when the device is used. ECG data andshock protocols utilized may also be uploaded to the phone forpresentation or transmission to trained medical personnel (e.g. firstresponders, emergency room personnel, treating doctors, etc.).

The embodiments describe above focus primarily on defibrillators thatare intended for use with a mobile communication device. The mobiledevices may be personal (e.g., off the shelf) cell phones, tabletcomputers, etc., or in some embodiments may be packaged together withthe defibrillator. In still other embodiments, many of the describedfeatures including the charging circuits, the dynamic dischargeimpedance detection, the discharge circuits, the housing form factors,etc. may be used in the context of more conventional defibrillators thatdo not require the availability of a mobile communication device inorder to operate.

Most of the described embodiments include one or more shock dischargecapacitor(s) that is/are individually or together capable of deliveringa defibrillation shock to a patient. In general, any of the describedcapacitors may be thought of as a capacitor unit having one or moreindividual capacitors that is/are configured appropriately to accomplishthe desired task. When more than one physical capacitor is utilized in acapacitor unit, such capacitors may be connected in series and/orparallel and/or in any other appropriate manner to perform the desiredfunctionality.

Several of the described embodiments contemplate the use of a transitoryelectrical energy store that helps maintain a continuous draw of currentfrom a power supply when a voltage boosting element such as atransformer draws current in periodic intervals (i.e., oscillatesbetween current shut-off and current draw states). The transitoryelectrical energy store temporarily stores electrical energy store drawnfrom a power supply when current to the voltage booster during thecurrent shut-off intervals, and supplies that additional current to thevoltage booster during the current draw intervals. It should beappreciated that the transitory electrical energy store can also be usedin voltage boosting designs that cycle between high and low current drawrates.

Although the described form factor provide compact designs making thedefibrillator itself highly portable and easy to use, it should beappreciated that a variety of different form factors may be used inalternative embodiments. Similarly, although specific electroniccircuits, defibrillator control logic and user interfaces have beendescribed, it should be appreciated that all of these features may bewidely varied. Therefore, the present embodiments should be consideredillustrative and not restrictive and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalents of the appended claims.

What is claimed is:
 1. A defibrillation unit comprising: a capacitorunit capable of temporarily storing and discharging sufficient energy todeliver a defibrillation shock to a patient; a shock delivery circuitfor discharging the capacitor unit to deliver the defibrillation shock;and a flyback converter for charging the capacitor unit, the flybackconverter including a transformer and a variable maximum transformercurrent control circuit that controls a current level at which currentto a primary coil in the flyback converter is turned off such thatdifferent maximum primary coil current levels may be set to facilitatecharging the capacitor unit.
 2. A defibrillation unit as recited inclaim 1 further comprising a defibrillation unit controller configuredto set the maximum primary coil current level to facilitate the chargingof the capacitor unit.
 3. A defibrillation unit as recited in claim 2wherein the defibrillation unit controller is configured to periodicallyadjust the maximum primary coil current level during charging of thecapacitor unit based at least in part on a then present measured voltageof the capacitor unit.
 4. A defibrillator unit as recited in claim 1wherein the flyback converter has an input voltage of no more thanapproximately 5 volts and an output configured to charge the capacitorunit to a voltage suitable for delivering the defibrillation shock.
 5. Adefibrillator unit as recited in claim 1 configured to be connected to amobile communication device that serves as a power supply for theflyback converter to facilitate charging of the capacitor unit.
 6. Adefibrillator unit as recited in claim 5 further comprising adefibrillator controller that sets the maximum primary coil currentlevel based at least in part on a current delivery capability of theconnected mobile communication device.
 7. A defibrillator as recited inclam 1 further comprising a defibrillator housing, wherein thedefibrillator housing holds a communication device, the capacitor unit,the shock delivery circuit, a defibrillation unit controller and theflyback converter.
 8. A defibrillator comprising: a capacitor forstoring an electrical energy suitable for delivering a cardiac shock toa patient; a current sensor for sensing a current drawn from a powersupply; voltage boosting circuitry configured to boost the voltage ofelectrical energy to charge the capacitor to a voltage suitable fordelivery of the cardiac shock, the voltage boosting circuitry includingan input switch; a transitory electrical energy store located arrangedto receive electrical energy from the power supply and to supplyelectrical energy to the voltage boosting circuitry; and a controllerthat receives a sensed input current from the current sensor and turnsan input switch of the voltage boosting circuitry on and off to maintainthe current drawn from the power source within a designated range,wherein when the input switch is turned off electrical current from thepower supply charges the transitory electrical energy store and when theinput switch is turned on electrical current flows to the voltageboosting circuitry from both the power supply and the transitoryelectrical energy store.
 9. A defibrillator as recited in claim 8wherein the controller is programmable to define the designated range.10. A defibrillator as recited in claim 8 wherein the transitoryelectrical energy store includes at least one of (a) an LC circuit, and(b) a plurality of capacitors arranged in parallel.
 11. A defibrillatoras recited in claim 8 wherein the designated range that the currentdrawn from the power source is maintained within varies by less thanfive percent.
 12. A defibrillator as recited in claim 8 wherein thecontroller turns the input switch off when the current reaches orexceeds a maximum current and turns the input switch on when the currentis below a minimum current and the minimum current is at least 97% ofthe maximum current.
 13. A defibrillator as recited in claim 8 whereinthe current regulating circuit is a digitally controlled currentlimiting Buck converter.
 14. A defibrillator comprising: a capacitorunit configured to store and discharge sufficient energy to deliver anexternal defibrillation shock to a patient; and a flyback converter unitarranged to receive a power input having a current of three amps or lessand a voltage of five volts or less and to boost a voltage of the inputpower suitably to charge the capacitor unit to a voltage suitable fordelivery of the external defibrillation shock.
 15. A defibrillator asrecited in claim 14 wherein the flyback converter unit includes aplurality of stages arranged in series, each stage being configured toboost the voltage of the stage's input power.
 16. A defibrillator asrecited in claim 15 wherein the multiple flyback converter stagesinclude: a first stage having an input voltage of no more than 5 voltsand an output voltage of approximately 12 volts; and a second stagehaving an input voltage of approximately 12 volts and being configuredto charge the capacitor unit to a voltage suitable for delivering thedefibrillation shock.
 17. A portable external defibrillator as recitedin claim 14 further comprising a transitory energy store, that serves asa temporary store for electrical energy drawn from a power source duringperiodic current shut-off intervals of a primary coil of the flybackconverter and as a supply of supplemental current to the primary coilduring at least portions of periodic current draw intervals of theprimary coil.
 18. A defibrillator comprising: a capacitor unit capableof temporarily storing and discharging sufficient energy to deliver adefibrillation shock to a patient; a shock delivery circuit fordischarging the capacitor to deliver the defibrillation shock; and avariable frequency flyback converter arranged to charge the capacitor.